1)The system represents the thing of interest, e.g. heat engine, chemical reaction vessel. This is distinct from the surroundings, which may receive dissipated energy if necessary.

2)Life support helps one to breath and not die, so that one can play more Fleet Operations
3)Improving shields and weapons is worth it. Screw the cost, your enemy will get the upgrades anyway, then will kick your ass.
4)I tried credit only ships once. I never tried again...

5)To my knowledge, no one has used multiple avalons in combat. Actually, I think Worf did it once, and he got his butt kicked.
I thank you for thanking me for my patience. In fact, I thank myself. Regularly.

Kind Regards,
The Doctor