I interpreted the point of the yellow and red "mainstream" techs as giving you a chance of getting the tech Early, rather than a chance at getting it at all. 

I suggest that you reread this:https://forums.elementalgame.com/368295

Warder

After the research breakthrough appeared, I think there shall be some notice how difficult the technology you can choose from are. I mean you can choose a red technology, but you don't see it is actualy red. The player sees red green etc. when he chooses the research path, but after that, several (possible) long turn passes - enough time to forget it.

Me too         I could just imagine the guy going: "AAAAAHH IT'S AAAAFTER MEEEE!!!".

It's things like that that give the game a soul. Just like the light from the taverndoor in the HoMM II opening gamescreen.

Uhm...but what if you want to create [mod in] a playable race like that?

My suggestion for how they should set up allowing "monsters" to wear armour, noting this is just for behind the scenes coding ease, as one way or another you want your weird monster to wear sensible looking armour you will have to model the armour to fit it. 

First is that you need a "body type" tag somewhere in the unit\model\race set up, (invisible to normal gamers obviously)
Second is that instead of simply assigning each armour piece a model, you would set up a list assigning a certain model to a certain body type.

These would then be cross-referenced when you tried to place armour on your unit.

The basic benefit of this is that you only ever have to have the one type of armour for all races, so that we don't end up needing "leather armour" "orc leather armour" "demon leather armour" "unicorn leather armour" as valid armour pieces, you just have "leather armour" and it figures the rest out for you.

incorrect ... demon-leather would be created from the Skin of a demon ... Humans and Demons can both wear "Cow leather and Demon-leather ... but it would probably be weird for a Demon to wear demon leather, he might rather want to wear human-leather.

Skin is Skin, its used to make leather. Tanned Human Skin is probably nearly as strong as cow leather or deer leather. Sure Daemon leather would probably be among the toughest, but Its more the process of creating the leather rather than what your source material is. Who knows, maybe human skin doesn't tan well, and doesn't recieve the process well in general. Its not (this skin is softer so its weaker) but (this skin can more easily be made into leather so its stronger). So it just depends. Obviously Deer and Cows have made it abundantly clear that they are excellent for making leather.