1) The "cover flow" effects are, at the moment, restricted to the B&N Store items, and books loaded from calibre are separated to a "My Documents" view. If you softroot your nook (think jailbreaking) you can get the cover flow effect on all books, and they all can be viewed in a single library. *However* the softrooted cover flow is a bit of a work in progress, and not really a feature I thought was worth it. I removed the softroot after a single day, personally
Having said all this, if you are wanting to get a nook you might as well buy from the Barnes and Noble store. It lack choice of formats, but its probably a safer option in terms of DRM, and the convenience is also there of just having it appear on there. Also the symmetry of using Barnes and Noble books on a B&N eReader. And this is coming from an Australian who has to jump hoops to buy B&N books
2) Regarding the button cracking, I haven't personally had a problem, but if you're really concerned I would do a poll around the forum. I believe this is also covered under warranty...(if this is false I'm sure someone will correct me)
3) It should be noted that the "Lend Me" feature is in beta, first. Also the LendMe is not solely on the nook but it is a feature tied to your B&N account, so yes it is restricted to the Barnes and Noble store. It also has a few restrictions on it too, like the fact that not all books support it AND each book can only be lent out once, for two weeks after which you will be allowed to read it again (you cannot open or read the book when it is being lent).
If there's anything else I and many others will be glad to help you out
