About soliciting reviews: It seems like the various review sites and blogs are quite up-front about whether they want you to query first or just send the book, so that's an easy decision to make.
I've read various people say that you absolutely MUST send AT LEAST a cover letter if not a HUGE press packet (which they would be happy to put together for you for a fee) whenever you send out a book. But you know what part of my job was when I interned at that journal that did book reviews? It was to open any package that appeared to contain a book, pull out the book, and throw away the envelope and any letters or packets that were not the actual book (and trust me, I did that without even looking at them--on a good day, I could get the book out of the envelope without even removing those papers). Then I looked over the book to make sure it wasn't about psychics and Marilyn Monroe, and chucked the books that passed that test into a big box, which went to the book reviewer, who decided what to actually review. The letters and (at times quite sizable) press packets never got anywhere near the reviewer.
So, I didn't include cover letters with the books I sent out. It feels weird because they have no way of contacting me, but on the other hand my Web address is on the back jacket, so I suppose they can if they really want to. Plus at least one of the Web sites is set up so that you can track the progress of the various review copies without actually bothering the people who work there.