Here's a quick guide. I don't have any numbers on damage/hp vs qvic, but I'd say if you can do qvic you can do tacvi...
I don't know the boss names, because they're long and weird and I refuse to commit them to memory.
Boss 1 - Will respawn at least once after dying.
Boss 2 - Spawns several small adds throughout the fight. Adds have very little hp, though.
Boss 3 - Dispells. Expect to have little to no buffs left after fighting this boss.
Boss 4 - Has a pet, can one shot the pet, don't know if there's anything else special about this boss. Sometimes goes invulnerable at 1-2% left, I think.
Boss 5 - Nothing special about this one, as far as I can see. Sometimes also goes invulnerable at 1-2% hp, can't remember for sure.
Boss 6 - Also has a pet but the pet dies fast. I think I've had this boss go invulnerable before, too.
Boss 7 - Nothing too special here, either.
Boss 8 - Spawns adds throughout the fight, usually 2-3 at a time I think. If you don't have a lot of hp this one might suprise you, he seems to hit harder than the others.
Attacking a higher numbered boss will cause all lower numbered bosses to aggro, unless they are already dead. So attacking boss 5 will aggro 4, 3, 2 and 1 also.
For tacvi armor the only requirement is the tacvi mold and qvic armor piece. Hand to the armor reward npc at entrance for your armor piece.
I never really paid attention to which bosses drop which items, but I think I've only ever gotten bracers from boss 1, and boss 8 drops ~4 armor items at a time.
Anything else I might have missed?
Edit: Respawn time is 1 hour. The message when you zone in says 2 hours, but that's not correct any more.
Naki