Originally Posted by
yogaflame
His healing factor has fluctuated over the years. Back in the Claremont days, it would have been possible to bleed out and die, but then we have also seen him regenerate after being nuked down to an adamantium skeleton.
As for 1) he has to be able to access energy(to convert to mass) from some outside source, because we have never had a limitation of him having to eat to regenerate vast amounts of lost tissues.
2)Drowning should work(classically), but then you have shit like the movies that say different.
3)Classically, he could not regenerate severed limbs, hence the reason his unbreakable skeleton was such a great deal. In the Ultimate universe he was ripped in half and his torso thrown far away from his lower body. He was able to track down his lower body by scent and crawl his way to reattach himself(but it seems he would not have been able to regenerate a whole new lower body).