That freakin popup is one of the biggest reasons I usually go egalitarian. Utopian Abundance prevents it from occurring (while also making all those unemployed pops modestly productive). Not the most universal advice, I know, but from what I've seen it's either that or halting pop growth on a per-planet basis - which obviously sucks for various reasons. IIRC you can't restrict apply species-wide population controls to your "primary" species, but I could be wrong. Even freakin gestalts have to deal with unemployment popups - why are robot drones expensive and micromanag-y to warehouse??
I'm pretty sure Social Welfare isn't sufficient to prevent the popup, though the pops are otherwise content and give a little Unity. There's lategame habitat/ringworld spam, but natural migration doesn't occur nearly fast enough to keep the unemployed from piling up.
As for corvettes...! Haha, I am probably so bad at the combat in this game. These are my two types of fleets:
A horde of corvettes.
Pros: Fast to move, low-latency to produce en masse, anti-piracy bonus, seem to trade favorably against equally "sized" fleets due to natural evasion and accuracy. Powerful weapons inefficiently "overkill" them, if they manage to hit
Cons: More likely to get destroyed. Enemy ships get a chance to retreat with every hit after their hull is damaged enough, which means most of them will escape the thousand-cuts
They seem ideal for capturing systems and "pushing back" enemy fleets, particularly with an alloy surplus
A mass of battleships
Pros: Bigass guns inflict losses on the enemy fleet, and low-accuracy long-range attacks are effective against starbases. Much less dependent on reinforcements, particularly with some form of regenerative armor or an engineer admiral.
Cons: They just aren't as effective as corvettes. Painfully slow.
So, great for stomping non-threats or for neutralizing star fortresses with less hassle, though the speed is annoying. Helps to have a gateway system up.
I'm sure these simplistic tactics would get me destroyed in multiplayer, heh! Like, I don't typically use PD, and tend to use shields, so presumably a fleet that goes HAM on missiles would wipe my corvettes out. Maybe corvette-clearing destroyers and cruisers are a thing, but the AI likes to diversify with a torpedo and PD and stuff. I dunno though... Sometimes I do put a PD on. It's a significant decrease in damage, but it's funny to watch ALL the enemy missiles get shot down. Probably worthwhile in a war I'm already winning.
The big question is what's effective against the end-game factions. I don't get there very often, the micro gets to be a lot even with Utopian Abundance. Using federations and/or vassalizing helps a lot with reducing my burden as a player, though sometimes that's a bit trickier than simply conquering is.
Not sure if it still works as it has been a few versions since I played, but you could actually kick and force vassalize one of the fed members and then conquer the other. You keep the federation and its bonuses, get two home worlds, and you don't have to compete with the other fed member. I did it in a multiplayer game once before and pissed off my friends because it let me snowball so much faster than them.
I bet it works! It sounds tricky to me, doing an invasion so early game, but I guess it's worth it for the pops and the second homeworld having good districts. I'm sure federation cohesion takes a serious hit
But that's still faster than working up the Diplomacy tradition.
I still giggle whenever I see the empire I formed this trade federation with. Totally Independent Bank, a 2-system sector released for tax purposes, then invited by us Tavurite Free Traders into the Intergalactic Free Traders. No creative bookkeeping/rebranding going on here
(Protip though: Trade collection auras don't extend through allied territory, only trade lanes. So I kinda goofed there - but soon Gateways will fix all that!)
The amazing thing is that they (and a third member) voted to let me use my diplomatic weight for decisions. I only had to call in one favor... an extremely profitable investment!