OK... this is meant to be helpful, though it probably won't sound it...
Firstly, no-one here is going to tell you where to find bootlegs. This is a public message board, and people in the Beach Boys' organisation read it. The best case scenario if someone posts a link to bootlegs is that that link gets shut down. Worst case, this board gets shut down. That said, Google is your friend.
Secondly, what the 'best' bootlegs are depends on what you're interested in. Someone only interested in studio outtakes would probably not be interested in the 1972 Carnegie Hall show or the 1993 Paramount show, while someone who wanted full performances of songs and wasn't interested in ten thousand partial takes of something would probably not be all that interested in the Unsurpassed Masters sets. Those are good places to start, though.
Smile bootlegs are, for the most part, obsolete now thanks to the release of the Smile Sessions box set last year. There is stuff on bootlegs that isn't on the box, but it's mostly only for the real obsessives, which you don't (yet) sound like.
And the three books you mention are, at best (LLVS) misleading (Priore has a tendency to mix fact with his often-wrong speculation) and at worst (the other two) outright fabrications.
The best books I've read on the subject are:
The Beach Boys FAQ by Jon Stebbins (probably your best first book on the band, a good decent overview)
Inside The Music Of Brian Wilson by Philip Lambert (a *very* thorough musicological analysis of Brian's songwriting in the 60s)
The Complete Guide To The Music Of The Beach Boys by Andrew Doe and John Tobler (a song-by-song analysis of the band's music, a little brief because of format restrictions, but with real insight)
Catch A Wave by Peter A Carlin (the least factually-inaccurate biography of Brian and the band).
You might also check out Back To The Beach by Kingsley Abbot, a collection of historically-important or well-written pieces on the band. Many are less accurate than the above, so caveat lector, but all are very readable.
Andrew G Doe (who is probably the single most knowledgeable person on the band I know of) has a list of books (up to 2001) and his opinions of them at
http://www.angelfire.com/la/Beachboysbritain/Bookshelf.html . I thought there was a more up-to-date version of the list on his website (
http://www.btinternet.com/~bellagio/index.html ), but I couldn't find it.
Bret Wheadon also has a very exhaustive list of books, along with his reviews of them, at
http://www.beachboys.com/booksIII.html . I disagree with some of his ratings (especially for Badman's book, which is largely plagiarised from Andrew Doe's site but less accurate than AGD is, and Bret seems to have read a completely different Beach Boys FAQ by Jon Stebbins than I did...) but he's read pretty much *everything* and so you've got a consistent voice there telling you about the various books.