Amazon Cloud Reader and it's Capabilities
 

(Pardon the n00b) Quick Questions

If I ever have an Amazon Kindle fail on me, I obviously can still access all my books through the Cloud Reader website but how would I get all the books back to newer Kindle device? Would I have to register that new device under my account? (then would the books automatically be available on that device)

Yes. I bought a second Kindle and was able to get all the books from my first Kindle loaded, though after a bit I realized I only wanted the ones I had not read. It's pretty easy to access your books and other stuff from Kindles registered in your name (I have 3 and sometime, but not always, they seem to sync up so for example Kindle #2 knows where I was when I stopped reading a book on Kindle #1).