You have an absurdly cheesy unit in your arsenal that, with careful management, makes starbase kills by the AI purely impossible.  Use Overseers repair ability manually, with lots of them.  They're useless on autocast, but on manual it's sheer hell trying to kill anything big against the Vasari.

It's like the Dunov for TEC is against the AI, but in a cruiser.

assailants. and skirantras.

So how obligated should I feel to research the shield, hull and weapon upgrades? And now that I know what my fleet consists of, what quantity of what ship should I pump out for initial planets?

I should also point out if you were surprised that the AI player was at the planet you were jumping to, you really need to scout more. I assume this was point blank, so that means the hard AI had at least cleared his asteroid and ice world already. While the hard AI gets a bit of an Economic advantage its not extreme enough to effect much early game. If neither of you attack your respective homeworlds you should be able to quickly take an asteroid and ice planet faster than a hard AI can.

It was Quick Strike. Probably the reason I didn't have it scouted was they killed off my scout and I neglected to build another one. It was also my mistake to speed up the game against a hard.

Oh and edit: I just beat another normal to test my fleet, but when I built 4 overseers they auto attacked and got slaughtered? How do I prevent that? Oh and regen bays, the carriers heal and the overseers heal made and unstoppable defense.

Ah thats useful, I forgot about that.

So basically get subverters to jump in and cripple, while the assailants enjoy the 25% increased sheild bypass. Oh and the subverter's passive 25% phase missile bypass doesn't stack does it? lol that would be so unfair.

Oh and can I assume I should refrain from buying off the black market a lot? I found myself doing that way too much.

just try to be first in fleet. thats a simple and easy rule. iv you are not the first build more fleet instead of other things. if you have the biggest fleet you can defend your planets. and try to research the two savagethings. so evey attack against you make you stronger.

It usually is, though.  Certainly there's something to be said for playing the long-term, but it's rare to be going on the offensive and win handily when you're behind in fleet size.

I said usually.

Those are significant wild cards, I will agree.  However, they need to vary by more than a small amount for a smaller fleet to prevail.  Faction also plays a role here; TEC will definitely have an edge with their hoshiko and LRM in the early-game, while Advent and Vasari will have more of an edge in the late-game.

The skill of the player is irrelevant to the strength of a fleet.  Of course a good player can overcome a disadvantaged position, but that doesn't change the fact that it's a disadvantaged position.

That's somewhat of a double-dip with tech researched.  The big ones are LF vs LRF and LRF vs heavy, which tend to come down to your tech level.

While these definitely have a huge impact on the actual outcome of a battle, they aren't strictly a measure of how strong the fleet is.  As well, outside of FFA, #8 probably implies there was recently a battle and you're just as depleted as they are...