1. True, but from a lore standpoint, you also have to consider that it can't be a quick process, harvesting an entire planet, and you'd kind of have to control it, as somehow I think the residents might not like you wiping out their entire planet.
2a. Absolutely. Even the Coronata will beat out the Vorastra, even microing won't help you (you can use MPJ to jump to it's side in a 1v1 where it has no guns while the Vorastra does still have guns on it's sides, but all this does is slow the inevitable). Heck, I even made a modded version where I made the Vorastra have Wave Cannons instead of Pulse Waves which I proceeded to buff by 15 or so per volley, changed Phase Cannons to only damage hull (particularly effective against an Advent opponent) and nerfed them a bit to compensate on average and it still got it's butt kicked by the Coronata. Sure, the Coronata has Suppression Aura, but still!
2b. Agree on the cooldown. Even at maximum level, I find myself wishing it was a minute or so shorter. It's so freaking long...
2c. The Maw is already sufficiently powerful as it can instagib frigates. The Vorastra needs help in the damage department, not TM.