Nothing to say that both patrellis are not alive. Nathan could have taken Peter into the upper atmosphere above the Atlantic and let go, flying himself to safety
It winds me up that Syler lived. He is a tough old sob. what is worse no one saw him crawl away.
Hiro will probably learn the art of combat from his hero.
Patrelli has the power of all the heros he has come in contact with, so he also has the powers of the Haitian and the voice control lady that was friends with Seresh at the beginning. He just isn't aware of them. He probably also has all of Sylers other powers too. But because Syler only revealed Telekinesis that is all Peter is aware of.
Syler does eat their brains. That is why he lobotomizes them and the head is later found to be empty. (as show in earlier killings)
I suspect that Peters pre-Issac-cognition dreams were something to do with the old guy he was looking after, maybe his power (maybe his mums)
I think Syler can levitate himself via his telekinesis which explains how he jumped so high when Matt Shot at him in the FBI headquarters when Syler attempted to get Molly for the "Second" time. This would also explain how he came from nowhere in the final battle (he was hovering)
Syler has much greater mastery of his powers than most of the people he acquired them from. This is due to him being much more willing to use them, but also due to his main power, the immediate understanding of all mechanical and biological things he is able to understand the way the powers work better than their original owners. (however we do see some bedding in time for example when he got the hearing)