Good point. But yeah, basically the ability is 'just' an enhanced form of the first one.

Some elaborations:
Let's say he and an average bob are fighting. Bob cuts off Kent's right arm, Kent kills him and cuts off Bob's right arm. Ken grabs Bob's arm and sews it to his stump, after an hour or two, it is officially 'attached' and he can begin really using it. Beforehand, he can't really do anything.

Let's say Kent and Superbob are fighting. Superbob does the same (cuts off arm), Kent does the same (Kills and cuts off arm). Superbob had super-strength, thus, Kent has somewhat increased strength (Yet definitely not to the point of Superbob's) in that arm, and only that arm. If he replaces that arm with another again, he loses the superstrength, yet gains anything special that new arm might have.

He can also heal over time pretty much any part of his body. Depending on the organ, it can take weeks to a full year, however. Larger parts of his body also need full replacements, E.G. he can just regrow his kidneys, but he can't regrow his arm, for that he needs a 'donor' so he has sufficient material to work with. 

He also can't regrow the more complex and important parts of his body, specifically his lungs, brain, heart, and stomach. For those, he's also going to need a replacement. However, he doesn't need to worry too much about if it's the right 'type' of heart or anything or if it's genetically close, it just needs to be a human heart. He'll be able to fix anything else himself.

However, there's lots of other downsides I'm thinking of to this. Obviously, if he attaches something with cancer, he's going to get that cancer, for one. For two, he basically has to prey on humans to do all of that. It's not like he's going to recieve too many actual donations, is it? It's also likely that his immune system is pretty much fucked when it comes to poisons or super-viruses. I mean, if it 'accepts' utterly foreign body parts it'll probably 'accept' anthrax or ebola, right? He'd probably live through that, but obviously it'll be a huge goddamn pain.

I'm not sure about too much else. Does that explain his abilities sufficiently? I think it does.

Edit: I just thought of something, lel. I'm thinking attached parts also eventually superficially turn into his 'actual' stuff, while being basically the same inside. E.G. if he attaches a black guy's arm (Oddly, that thought is hilarious to me. Is that bad?), it'll turn white in a few days.