I'll give this a shot. IMO:
1. Marauder DPS > Veng Jugg DPS. If properly geared, the gap can be narrowed a lot, but Mara will be higher.
2. Heavy armor = much less squishy.
3. Anni spec will help with that some, as will the fact that they have a lot of tools for survival. If you're that worried about survivability, use Quinn for the tougher fights.
4. Except for certain fights, this is what I did, at least up until about Belsavis. Keep them geared properly and you should be ok.
5. cool.
6. Advanced class didn't seem to matter to the story one way or the other. It's a fun story no matter what.
Hope this helped. YMMV.