Yep, they do for each individual conflict, and the number they get goes up with how strong their military is (don't know any numbers, it just seems to be what happens...)

Build a fleet of two or three medium+ sized ships with a ton of armour and plonk them on top of an undefended starbase near near the Drengin's territory as bait. I watched two of my frigates go from level 1 to level 17 in two turns... Quite funny to watch, as the occasional hits get through your armour and they gradually eat away at the hit points, but they send dozens if not hundreds of the ships on these suicide attacks against a useless starbase. Yes, it's exploiting the AI, but frankly it deserves it for slowing down the game.

Someone more experinced will need to confirm this, but I don't think the individual corvettes ever get any better - just more and bigger fleets. One of many reasons to take the Drengin out early.

The Drengin super ability is one of the most annoying in the game. It's useless later on for any purpose but lagging the system (unless you have a bizarre strategy based around cannon fodder units) and early in games with slow tech development, it's blatantly overpowered.

It would be much better if the number of ships you gained was decreased significantly, and instead, the ships were using the technologies you have researched. The ability would be useful all game, it wouldn't result in the annoying "blob of doom" mechanic, and the ships you'd get would correspond to your weapon choices instead of always being cheap mass driver armed heavy fighters.

I like to gift them to my future conquests and watch thier economy crash trying to support them. When I declair war I just get a bunch more that I send to my next victim.

It's probably a bad sign that one of the first things im going to do when TA is fully out as far as modding goes is make the Drengin and Korath more seperate, and give them a real super ability - Super Dominator sucks.

Yes, it can be very annoying if you don't deal with the Drengin threat early on, and there's so many ships near their homeworld that your game starts to crawl when you're focused on that section of the map.

Anyway, just research defense for whatever weapon they have on them, build a couple ships with heavy defense, and wipe them out. You can wipe out every single fleet with one highly defended ship.

I see what you mean about the ships being useless later in the game. A single medium hull with Kanvium and Positronic Torps just took out 150 Super Dominators in a single turn, losing 5 hp in return.