Inherited my grandpas old guns, he kept them in his soggy, humid basement for years

I’m not a gun person, I of course know the basics of guns and obviously know gun safety but I am really bad when it comes to knowing what models something is, getting parts, gun maintenance or anything like that. I do know the top one is a 30-40 Krag, next is a 30-30, second to last is a single shot bolt action 22lr, and the last is a single shot 16 gauge. Some of the guns have rust and discoloration on the metal, and the 30-40 krag has a hole in its wood on the barrel and the wood is also bent and morphed at the end. I don’t know what to do about the rust and discoloration without harming the gun. I’ve never done anything like that before. I want to get these guns back to how they used to be. They really are kinda nasty and gross at the moment