You all went on BP multi again?! Send me a PM next time!
General:
- Reverse afterburners don't work; even in co-op. Intentional?
No, that's not intentional. I remember them working fine when we tested it the other week... strange.
Stained Mars Red:
- Archer and Paveway don't appear to damage turrets and subsystems as effectively as in single-player. Perhaps the corvette is just more sturdy than I imagined.
That's exactly right. The corvette in that mission has double normal hitpoints. Next update will have reduced hitpoints and more baddies to fight.
Karuna dogfight mission:
- Players respawn right next to each other. Initial spawn is fine.
That's an unforeseen bug specific to Karunas in dogfighting missions. The mission was initially intended for one life per player. I currently have no clue why Karunas do this over fighters.
We just played a couple rounds of this TvT in capships, it's okay but the hugfighting is a real issue and using ETS in multi TvT seems to cause turrets to stop firing. 
That sounds like a lot of fun! Team play would seem to open a new window for strategy in capitol ship fighting. Sorry to hear about the ETS.
You all play Kir2yar's mission?