Hey Edwin.
I'll try to answer some of your questions briefly, although I have to point out that the hypothetical situation you've made with no competitors and no black market would completely defeat the purpose of the game as you won't have any objectives (usually your objective is to make the most money so you can buy out your competitors before they buy you out)

1 a) it is essentially equal to autosell resources then buy other resources on the market for the same price (ie you are better to produce the resource with the highest profit, then sell it to buy up a cheap resource that you need.
there are a few reasons why its helpful to be self sufficient
-) if prices rise, you are still making the resources you need to upgrade so can just wait until you accumulate enough to upgrade without having to buy them at super high prices.
-) if the price of the basic resources you are producing drop (from competitors selling too much of them), then you might not be able to make any money off them, but at least you will still be able to use the resources to upgrade, which you needed to do anyway (eg iron/steel, aluminium, glass), or carbon instead of iron/steel if you are scavenger
c) yes you will definitely make more money that way, although the prices of resources you are consuming will keep rising and you will therefore accumulate more and more debt if you ignore them. Also, if no one is consuming the resource you are making its price will eventually fall as you sell it off.

2) a) when you have spare cash early on you have correctly identified that you have a few options. As a general rule, the best way to use that cash is to invest it in something that will help you to make even more cash. this will vary each game, but often will be a special building, particularly rushing to an offworld market, although any of the other special buildings are good.

generally you don't want to waste that cash paying off your debt unless you are in C or particularly D debt, as the interest penaltly multipliers get a lot more painful at those levels of debt. You are better investing the money to make more cash than paying off debt if you a B level debt or higher.
Buying your own stock is certainly worth considering once you reach HQ level 4 or if you can see an opponent may be close to buying you out. Essentially you need to ensure you have bought up to 5 of your own stock before anyone else can take you out by majority buyout (by buying 6 of your stock)

The only reason you should buy someone else's stock early game is if you think you can complete a majority buyout on them, which means you have to buy 6 of there stock before they can defend themselves. If you attempt this and fail (ie they defend themselves in time) you should definitely sell back out of them and use the cash to invest in something that will make you more money such as an offworld or technology/upgrades

its best to pay off debt only if you are C or D debt almost 100% of the time

c) debt is not free. once you hit D debt 3 things happen 1) you cant use back market, 2) the daily interest payments exponentially increase, 3) your stock price will fall dramatically the further into D debt you get. Once you reach around $200,000 -$300,000 in debt, your stock price will probably be very low, which makes it extremely easy for a competitor to buy you out and use you as a nice subsidiary to earn them money and boost their stock price.

I hope that helps...

Thank you for the reply.  I am trying to make this artificial so that people aren't tempted to give actual good game advice rather than exploring the mechanics.  (I want to know what the financial incentive is versus the strategic reasons to figure out the tradeoff.)

#1 seems answered -- you buy and sell at the same rate.

#2 has a couple of points:

* It sounds like there are two concerns -- maximizing your profit and preventing a buyout by increasing your share price.  (I was really disappointed that I don't get the cash when someone buys my own stock from me.)

* I would look at daily % returns on three things, and compare against the highest rate X: (When I played, I noticed I was paying 30% interest/day.)

** debt -- X% per day is the profit you get from paying off debt.  Can you do better than X% return in one day?

** stockpiling resources -- is the price going to go up by X% in one day?  If so, then stockpile.  Otherwise, sell and use that cash on X.

** buying stocks -- is the stock price going up by X% in one day?  If so, buy now.  Otherwise, invest now and buy later.

** investing in your business -- Can you get X% returns tomorrow on cash spent today?

What is a reasonable estimate of how much return you can get in one day for each dollar you spend?

As for buying other players' stocks, the article made it sound like that first block of stock really increases your share price.  It made a good argument how buying someone else's stock is a good defense against being bought out yourself.

Yeah, this probably make sense thematically, but in practice, it was terrible. Basically, as you bought out someone's shares, you were giving them a lot of money, often enough to buy YOU out. Thus, it led to situations where the game was over long before it actually ended. Buying your own shares can still be a good idea, however. Think of it like buying a shield or extra HP.

Wow, you really are active on the forums.  That makes perfect sense, and I support what makes a good game, even if it isn't completely realistic.  At the same time, I thought I was being clever and was disappointed that my cleverness wasn't rewarded, and it does run counter to the notion of "owning" that stock.  Ultimately, I can live with it, but I wish I hadn't found out the hard way.

Hey again Edwinkarat - I'll try to answer your further questions: Sorry if it goes on quite a few tangents.....!

2a) yes, you are correct about 2 of the main concerns in a multiplayer game of OTC. Of course, the 3rd main concern is to buy out your opponents, although I suppose that goes without saying. This 3rd concern is particularly influenced by how many players there are in the game. eg in 1v1 - if you can fully complete a buyout against your opponent at ANY time, then that is obviously the best move. whereas in an 8 player game, if you can complete a buyout against 1 of the opponents (not all at once), then there is a high chance it may not be the right move (especially if you haven't defended yourself first), as you should be more focused on defending yourself from the other 6 players first, and maximising profit. Buying that player may give you some dividend revenue and raise your stock price which might help objectives 1 and 2 in the longrun if it is a useful subsidery, although only do so if it meets the first 2 criteria, or you see that opponent as a threat you need to eliminate.

if you want to win games you need to stop focusing on daily returns and focus on returns per 10 minutes (game time) - which is 1 second real time. The prices of everything in the game change every second, so its impossible to calculate a daily return accurately anyway (unless you average out things from the previous day which would defeat the point).

c) you cant just look at total profit from paying off debt. one concept that new players to this game all struggle with is how valuable cash is. An example from zultar is that $2000 cash plus $2000 debt, is much better than 0 cash and 0 debt as the cash can be invested into profitable buildings. To further emphasize this, if you could cheat and have $100,000 of cash and $102,000 debt on day 1, rather than just $2000 cash (the usual starting cash), you would have a huge advantage. Aside from immediately buying out your opponents, you could, for example, upgrade straight to HQ level 5, upgrade to level 4 and build an offworld launcher, get an early patent lab and teleportation etc. You could then make huge profits right from day 1 and kick ass.  

Its a fact that cash is much more valuable than "negative debt", sometimes up to 10x as much (it depends on a lot of factors!). That is why you should only consider paying off debt once you reach debt level C (or usually D), as the 30% interest tick at that level starts getting relevant. However whether to pay it off also depends on your cashflow. If you have a very, very low cashflow, it would likely be better to take the 30% interest debt hit and invest the cash in profitable buildings (to get more cash), than to pay your hardearned cash into your debt and have no way to increase youre cashflow.

d) there are a lot of demands on what determines a resource price. stockpiling is certainly useful if you think a good is below its market value, or you think its price is going to rise. things which might affect this are if the good is scarce (eg a map with low silicon which you have a monopoly on), the demand of other players for the good,  if the colony is using it (it pushes up the price of some goods - it changes each game. move mouse over it to check) etc

e) stock price rises are usually very small compared to anything else. As duelking mentioned, you only get a dividend for stock if you can fully complete the buyout on an opponent. you don't get any dividends for just holding stock.

f) YES - this is almost always the way to go. The "basic" strategy is to upgrade/expand as fast as you can by making the most profitable goods then get an offworld at HQ level 5 to make huge profits, and later an upgrade lab with reasearch to increase your production of each good.

One final point I'll make is that debt is only relevant if your opponent can use the effect it has in lowering your share price to buy you out.

If you can restrict your opponents cash completely, it doesn't matter what your debt is, You could have $500,000 in debt and a share price of $5 per share, but if he can't afford to the cash to buy you out, you can buy him out first and still win.

Hold control, and the buy button will turn into a sell button.
You can also autosell resources by holding control and shift and a little minus button appears next to them. This is extremely important, as it means you can set your most profitable resources to "autosell" into cash, which makes sure that you get maximum profits for them, before your competitors can bring the price down.
It is also the preferred method to sell life support resources (ie water, food, oxygen), as it means they will turn into cash, rather than getting eaten up by your life support system (which effectively would otherwise come out of your debt)

That should never happen. The icons number will always be less than the actual buildings icon, because the icons number is net profit without factoring in adjacency bonuses. That's the only difference.

Maybe it's a Scientific HQ, which ignores the cost of Silicon when showing how much a Glass Kiln would make?

So, if I followed this advice, I would never stop bidding on an auction because debt doesn't matter.  I would also auto-sell everything, since the cash flow is more important.  (Actually, I really do best when I auto-sell everything, as that gives me cash flow faster, and you get more money than stockpiling and selling all at once most of the time -- plus, you don't need to spend attention on it.)