Minsc got killed in the city sewers fighting the dwarf gang there. In the heat of the battle Keldorn stumbled by and asked to join. I said yes and switched (the now dead) Minsc for him.

Much later I learn that Keldorn is leaving at some point (after finding Imoen?).

Now, I'd like Minsc back when this happens but he is disintegrated down in the sewers... is there any way to bring him back? If he left a body there would it stay there indefinately?

I haven't checked for corpse yet because I'm far away doing epic deeds :D If it is there I can res it no problems but if it isn't... Could I use a cheat as a last resort to respawn Minsc?

If not then I just grab someone else :)

There is no way to bring him back. If you remove someone from your party and they are dead at the time you can not raise them.

Keldorn will not leave your party unless you tell him to (with the incident with his wife) or if your reputation gets too low. Keldorn is arguably 'the' best warrior in the game with his insane class abilities and being the only character capable of wielding the most powerful melee weapon in the game. You will not want to replace him.

I want to keep Keldorn yes but he talks about leaving after we find Imoen. I let him have one day with the wifey and after that he was a "new man".

But if I actually don't have to let him go then problem solved, thanks :)

when a person is discintegrated, their body turns to dust
Keldorn only leaves if you let him
so if you wnat a fighter type NPC, you can keep Keldorn or get Valygar

Ivellos... Chorde didn't say anything about Disintigration. Minsc just died and Keldorn came by, asked to join and Chorde said "yes", so that automatically dropped Minsc because he was toast.

Anyway, keep Keldorn. He'll stay with you for the whole game if you choose the right dialogues.