So, I've done further research to what Cruelsader has found. I'm playing as a Terran and nearly researched everything, just last missile and starbase upgrades left. I'm omitting speed upgrades from the list. And if you don't see what kind of hull that was, it's a huge one. I'll only say if it's one of the small or tiny ones.

My fleet setup is:

Tank:

+25% defense on own influence*

warp bubble*

1-2 weapons

2x +8 hit point upgrades

rest defensive components

Fleet Offense:

Small Hull

+20% fleet offense*

Fleet Defense:

Tiny Hull

+30% fleet defense*

DPS x3:

+50% offense on own influence* (tested this with one ship, check screenshot)

rest weapons

So, this is my setup. Things marked with a * at the end are possibly aggro factors. Results:

-Tank ship is tanking, taking all the hits. I guess, Warp Bubble is also considered as an aggro factor, last test I did was done with a tank ship with only +%defense, my other dps ship with +%attack got hit.

-I CONFIRM that fleet bonuses stacks with indivudial ship bonuses (well, who am I to tell this to pros here, while I'm only a noob

-Possibly found a ship detail bug in fleets

Bug:

I really don't know how can I explain this, but ships with +X% offense/defense bonuses, they seem to add component bonus to a base of zero. You'd say, it's a fleet defense etc, but even indivudial bonuses give a bonus to other ships... (take a close look at the screenshot below, you cannot get 500ish beam on a tiny ship right? )

SS:

http://img87.imageshack.us/img87/6032/56525328az3.jpg