First, when you start a Rebellion game, it is clearly wrote on the screen "not for review"...
Now, when you type in google "Rebellion Beta Review", the first link from the result is your post... you make a bad publicity for a game who is only in early beta stage... maybe change you title with "my rebellion beta testing-Lame!!!"
As the corvette, they are perfect against titan, along with some other ship... when i have corvette, it seem that titan try to kill them before my capitalship... and i am not sure about it but it seem that repair rate of titan is slower with corvette around... with 50 corvettes and 3 capital level 4, i was able to kill a titan level 3... sure almost all corvettes was killed and my capitalship barely alive but it have work...
As for AI attack... it is very variable... sometime, they stay home and sometime they work together for a massive attack... have loose a game when 3 titan from 3 different AI have attack my homeworld...
For the double starbase, i have see AI use it... but not in the way who make the double starbase a hard nuts to crack... i mean starbase near each other with the boom thing who allow them to repair each other...
As for the new TEC cap ship, it was almost good in 0.60 by capturing orbital structure... feature removed in 0.61... best to reintroduce it and make the capture orbital structure functional when capture... in place of destroy the orbital structure of a enemy, and build your own when you capture the planet, it will spare you plenty of money/metal/cristal by capturing enemy structure... resource that you can use for increase your combat fleet, make some research or upgrade planet...
remember that beta testing is about find problem and report to the devs for allow them to correct problem... best to wait a RC ( release candidate ) version for a review... or better, wait the public release with a game with less bug, more balance and tuned in function of beta tester report...