I had a cat that acted like you where murdering him to moment you tried to clip his nails. I think he had a bad experience at the Vets or something and associated the whole thing with a lot of pain. The trick is the break the process down. Forget actually clipping for now, just get him...
Sounds normal to me. All three of my cats do this not only to the sheets, but also my belly! I think it is simply a comfort thing. As far as the peeing thing... I have no clue about that.