So Peter absorbs Sylar's abilities (Evident by the telekenisis when rescueing Mohinder). However, how is he not crippled by the advanced hearing, something he wouldn't have been able to control at first?

Maybe because in Peter's case the power activates only after he becomes aware of it. He knows that Sylar has Telekinesis, and that's why he's able to use it, but he doesn't know about the Enhanced Hearing, The Cryokinesis, the Liquefaction, the Eidetic Memory or any other power that Sylar may have stolen.

Peter's power works through emotion. He uses the feelings he has for the person to connect with their power, but in Sylar's case he only knows that he has Telekinesis so he only connects to that. If/when he learns about Sylar's other abilities, maybe he'll be able to activate them as well.

It seems that that is the case, Peter also has Eden's power of persuasion but he cannot use it if he doesn't know he has it so superhearing probably cannot activate until Peter realizes that he has that ability

I agree with everything that was said here. I think Peter has to see the power in action to kind of know that he has it. Like, he knew that Sylar had had telekinesis when Sylar used it against him in 'Homecoming', but he probably hadn't realized there were other powers. I'm sure he might tap into them a bit more as time goes on. But that's definitely a good question. I, for one, am excited to see what else Peter'll be able to do.

thats a fair explaination, but it has one flaw I think. When Peter saves Claire in Homecoming, he 'dies'. Before his death, he knows nothing about Claire and her power...yet still manages to heal

Claire's ability is completely different. It doesn't have to be crafted or controlled, it's automatic. Claire can't tell her body to stop regenerating. However, it is questionable since in "Distractions", Peter told Claude he had to think about Claire to use her ability, but that was probably just an inconsistency or mistake by the writers.

Exactly there are different levels (is that the word?) of abilities like some are just natural and others have to be focused

Yes, I think it would be levels. Or just different types in general, and, like Claire, or Matt, they're more natural than anything.

Yes exactly, Matt's ability would be another example that I forgot

Yeah, and he'd had his brothers powers for years without knowing it and without using it....perhaps it takes a while to learn them. Sylar however, his power is knowing how things work, so any power he takes he would know how to use it to maximum effect immediately.