I can only respond to 5 of your points.
1) To compete with Barnes & Noble's nook, which recently dropped the price of their 3G/Wi-fi regular version to $199 and introduced a new Wi-fi only model for $149. Hence Amazon's own recent price drops and new model introduction in response.
2) I rather doubt it. Your Kindle is not connected 24/7 if you turn off the Whispernet, and I'd hate to have Amazon's 3G data bills if they tried mining people's Kindles for information that way.
4) Because the books are backed up in the Amazon-hosted account archives which are normally accessed wirelessly and people are often in the habit of deleting books off the Kindle once they've finished them, so the next time they synched, they "lost" the removed books, which, incidentally were accidentally sold in the wrong copyright region and had the cost refunded anyway.
But anyone who'd downloaded a backup copy to their own computer could have easily restored it to their Kindle, and there's really nothing Amazon could have done about it.
5) Again, you can turn Whispernet off. I rarely bother using it because it drains the battery.
6) Yes, the "duokan" people have apparently created a Chinese-language interface
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