Maybe that's why he hasn't just gone ahead and blown up already. Did he see her in his lurking about?

In the original future, it was Sylar, who had killed Claire and thus could blow up without dying.

you mean in 5 Years Later? it couldn't have been Sylar, he didn't get Claire's powers until after he turned into Nathan.

I'm not entirely sure how Sylar intends to blow up and then become President without Claire's power.

I don't think that he intends to blow up. I think the idea was that Sylar and Peter both have ted's power. Peter loses control and blows up the city. Nathan blames Sylar because he can. At some point later, Sylar takes Candace's power and then kills Nathan and becomes president.

That "boom" does not signify intent to blow up? I suppose he could make something/one else blow up...

Does the person with the nuclear powers even feel the effects of their power? Because Ted didn't look any worse for wear after destroying the Bennet house (oh shit! someone remind me - did Mr. Muggles get out?).

you mean in 5 Years Later? it couldn't have been Sylar, he didn't get Claire's powers until after he turned into Nathan.

OK, one more time. The "original future" is the one that Future!Hiro experienced. In that future, Sylar did kill Claire at Homecoming. By warning Peter, Future!Hiro prevented this "original future" from happening. But in 5 Years Later we learned that this change wasn't enough. NYC still went boom, but it was Peter who did it instead of Sylar (even though Sylar was blamed for it). Now that Present!Hiro has seen that "second future", he can hopefully change things more so that he kills Sylar and prevents Peter from exploding.

Yes, he was staying in a kennel after the explosion. Although, really, if Mrs. Bennett were an actual dog-show person she would have found a hotel that allowed pets.

But in 5 Years Later we learned that this change wasn't enough.

but, Claire was still alive, wasn't she? with brown hair?

What we saw in 5 Years Later was the future after Claire was saved. Future!Hiro experienced the timeline in which she wasn't (hence the going back in time to tell Peter to save her).

The season 1 dvd set info now with artwork.

So, let's see. The Original Flavor timeline is the one in which Sylar killed Claire and then blew up New York himself. When Future!Hiro meets Peter on the subway, that's the future he is trying to alter with his "Save the Cheerleader, save the world." In the 5 Years Later future, Peter managed to save Claire and pick up her healing powers. He was also the one who blew up New York, but Nathan lied and covered it up saying that Sylar had done it. Some time later, Sylar, after meeting and killing Candace, killed Nathan and began impersonating him. When Present!Hiro met Future!Hiro in the Five Years Later future, FH didn't know that Peter was the one who blew up New York. He thought he had been a total failure, but he hadn't. He did manage to save Claire, but he didn't stop the city from blowing up. So now Present!Hiro is back in the present trying to get everything right and stop New York from going boom. The problem I see with this is that Sylar isn't actually the one who blows up NYC in the Five Years Later Future. So, it seems like Hiro could kill Sylar and still have NYC blow up. New future because Sylar won't be around to kill Nathan and commit hero-cide, but sucks to be a New Yorker all the same.

So confusing. Time travel makes my head hurt-y.