Fleet tactics

Depends on the roles assigned to the ships. Ship roles are actually very powerful. Depending on a ship's role, it will preferentially target other ship roles, so you can build escorts covered in defenses and they will tank the damage while lightly-armoured gunships pound the enemy unmolested.

What is the advantage of making smaller ships very fast? Will they get hit less often because of their reduced speed?

According to shiphullstatdefs.xml, it appears that the larger the ship, the less natural acceleration it has.  That can obviously work against you if you have a mix of ships however.  Besides other typical modifiers, I dont see any relavent differences between the ship classes.

However, it looks like it would be quite easy to mod in a natural jamming capability for each ship hull, making smaller ships more difficult to hit than the larger ones....which makes a bit of sense. That could make smaller ships a bit more relevant in the mid game, where usually its large ships that rule space.  Of course, this would make carriers even more ridiculously OP....

What is the point of giving your ships thrusters if ship speed doesn't matter?

Excellent point. I would love to see thrusters increase the dodge rate of the ship as well as the speed.

On one of the weekly dev streams, one of the devs suggested that the current speed of the ship does affect how often it gets hit. I have not seen anything suggesting that in game however, so if it exists, it must not be a very big effect.

Well at the least, you would want to increase the speed of ships relying heavily on short range weaponry, such as kinetics. Thus reducing the amount of time they are being fired at without returning fire.

It also might be needed if you plan on mixing hull types and want all ships to engage simultaneously.

I'm still unclear about the fleet mechanics and what would be good or not... but for example, a anti-support ship (interceptor?) would want high speed so as to reach the enemy support ships quickly.

I am a beam boy.  I just like the way they look.  Therefore, to help reduce the Range advantage from enemy missiles, I try to put on thrusters so I can close the range gap more quickly.  Or, another tactic is to build your beam ships as interceptors.  They are practically in range with their beams right away.

True about an interceptor having high speed to get to the support ships, however you have to nearly destroy all of the other enemy ships before you begin to fire on the support ships.  I think its better to keep all of your ships together, and destroy each enemy layer, one at a time.  Like I said, I put ALL of my ships as interceptor (except MY support ship(s)), just to close the range quicker, due to the start locations based on ship class.

Makes sense. 

Honestly the system doesn't feel great to me right now... it feels like I'm playing rock paper scissors, but rock just doesn't break paper all of the time... and then the whole extra layer of rock paper scissors with the weapons/defenses.... but then mathematically (or so I've read) its just better to go with more weapons and HP.

I'll avoid saying anything too specific, wouldn't want to start another discussion on tactical battles, but I'll just leave it as "I think the fleet tactics need a little more transparency and work to get right"