1. The meaning of "rallied enough" would depend upon the context, and perhaps the sentence that came before it. He was able to gather enough of something (support, funding, etc) in order to be able to show the new iPad2. The "slightly lighter" bit means in comparison to the older iPad, this one weighs less. 2. "Go through" is to look at. It also implies that the person is looking for something (mistakes, etc.) and will look at all the photographs in order to make sure they are correct. For instance, if I say, "I'm going to go through these papers," it implies that not only will I look at them and read them, but I will check them to make sure they are correct. 3. "Rallied back" means that he recovered from his illness, at least temporarily. Hope that helps.

Hey, 1) I think he collected enough of "something" that revealed a little more spry. I don't know. 2) Issacson and Jobs were just looking at photographs, or "all photographs" 3) It mean that he manage to recovery besides of almost dying.