I don't know about understanding them just by looking at them. Isn't the whole point that people are not born the same, I think that was even the tag-line at one point. It doesn't make sense Sylar is able to just have every single power naturally. Now there is hardly a debate that Sylar power is the analyze/understand people. I know adding other people's brain to his sounds kind of silly(well with alternatives being brain eating or permanent mimicking, what isn't silly ;p ), but I think it fits in very well with the whole theme of the character... here is the part where Sylar kills/meets Brain Davis after showing him his power: Quoting so it's easier to see...
*Cup moves slowly*
Sylar: Incredible...
Brian: Can you make it go away?
Sylar: Why would you want to do that? (emphasis in not understanding in his voice)
Brian: I don't know what this is... who I might hurt... I-I don't want it.
*shows a clip of Sylar examining/building the watch, but from the watch's point of view*
Sylar: You're broken.
Brian: What?
*Sylar hands the book to Brian and moves behind him*
Sylar: Mr. Suresh was right. It's so clear now. How it all works. Pieces fitting together... it is in the brain.
Brian: So you can help me?
*Sylar looks at... *whatever that crystal thing is*... and picks it up, Brian is not facing him, looking at the book*
Sylar: Don't worry Brian. I can fix it. It's an evolution imperative.
*Sylar bashes him on the skull. You hear a lot of clockwork. Sylar puts on his glasses he uses for building watches and he slowly gets closer to the knocked out/dead and bleeding Brian*
Okay first off, some debatable things:
1. Sylar examining of Brian. It might have been his "brain scan", which I really believe it is. Potentially it could have been Sylar's psycho side kicking in, seeing Brian as some kind of weakling and ungrateful person. While, I really believe it's the first thing, I'm starting to think it might be both. His final scene, "Let's tell all those people they are special"... he could be trying to trick Surresh.
2. It's all in the brain... pieces. This is pretty much the main thing about my theory that Sylar's use of the brain is that he takes the piece he wants and adds it to himself. When Mohinder and Eden entered his apartment, Eden spots a surgeon's manual by Sylar's desk, it's open to a page talking about brain surgery.
3. "Evolution Imperative"... Sylar says that as an answer to Suresh's question "Why don't you do what you want to do?" in an earlier scene. He describes how sea turtles are meant to die in the same beach they were born on, spiders eat their young, and lions slaughter gahzels(totally spelled wrong), "they don't want to, they have to". Could it be that Sylar sees Brian going against nature's order and then kills him(see #1) or could it be he seems himself as something different now, that he was living the wrong "imperative" all along(as he hoped) and that his true mission is to 'fix' people, which is just a twisted way of saying kill them.
One thing is for sure... he did not gain the power just by looking at the guy and he does has somekind of use for taking the brain out.
I think Sylar has very limited range on his "brain scanning" powers. I think he does use Surresh's map, and Claire's name does get removed.
About Claire's father, Mr. Brennet... he obviously knows all about them before his encounter with Saresh. Isn't it obvious by now? ;p He is a manipulator... there is probably no one who knows what's going on in his mind, even the Haitian might be his puppet.
I don't think Hiro, lost his powers. He might of been too depressed to use them. The power could have restricted him going back to the same time twice or something, but I doubt it's just gone like that.
Finally, Charlie, her power might be a lot of stronger than some people make it out to be. She can lead to read Japanese in a whole day. She is a super genus pretty much. Now imagine someone like Sylar, who knows where most of the heroes are at and can figure out how something works just by focusing on it... it could be quite a power. He would no longer need that map, and his main ability could even improve. Makes me curious though... did Hiro prevent Sylar from killing her? I don't think so. The only thing that changed was the picture.
I also don't like why people are being so critical about the episode. It was really good ;o! It's hardly an unimportant episode, I think we've learned more in this episode than we did in any others... and damn, Sylar is just awesome. I guess, the whole "too many characters" deal might be annoying, but it's not any different than what we are used to, I'm just glad it's at least one hour. As for the money and Hiro thing... I think his father is rich and somewhat important. The man who played the Asian guy from Startrek, who later came out of the closet, is going to play Hiro's father.