2) The AI does not really seem to bother with researching and building up its starbases.
Too true. I'm running into this issue now for completely different reasons, but the AIValues for the fortification techs, as well as the military starbase techs, are just too low. In fact, they're even lower for the military techs (defense/attack assists), and since the military techs require the fortification techs in TA, the AIs never get around to them.
For example, a good all around algorithm for building up say an Economy or Military starbase might be something like:
Although I still haven't used it, my understanding is this is somewhat like the "starbase management" system works. I see no reason why the AI would not be coded to use it as well; it seems as though this is just a problem of it not having the techs.
Granted, it doesn't build enough economic bases, nor put enough modules on them, and it does like to spam influence bases, but if it doesn't have the techs, it doesn't have the modules.
The general consensus among the community is that the starbase upgrade system needs an overhaul, though. Most seem to be behind some sort of system where a constructor builds the starbase and the starbase handles upgrades from there, although there are infinitely many ways to resolve that, with ideally most of them taking some kind of time and/or resources, so you can't build up a base whenever you want-but it'll be more efficient than the current system.
The other issue, of course, is that starbase weapons and defense modules are completely useless by midgame. Even a fully decked out starbase will fall to a ship as low as a 40-50 attack medium hull, assuming it has proper armor, most of the time, and once you hit 100 attack it's all over.