I just finished (listening to) The Windup Bird Chronicle, and

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I just finished (listening to) The Windup Bird Chronicle, and I absolutely loved it!
As I'm not very good at noticing subtle threads in stories and am not an avid reader in general, I have a few questions that you guys may be able to answer.

What were these powers of Noboru Wataya's? Is that ever hinted at? As far as I noticed, it's only mentioned that he controls his sister with them, nothing else.
What was this other world in the hotel, and who were "they"? Is this ever mentioned?
What was the deal with alternate world Kumiko, and why did she speak with different voices? Why was she so scared of Tooru seeing her or the corpse of who I assume was Noboru?
What did the Zoo and Manchukuo stories have to do with anything? I enjoyed them a lot, but I can't see the connection.
And finally, what is the windup bird? What does the sound of it mean?

I'm starting to feel that I might have missed some very important parts of the story now that I write my questions down.

I'd also love any recommendations of similar style, though I've heard that Murakami's other works are not like this one at all.