I'm afraid most of what you're looking for would be in the realm of hacking, and the ... creative individuals (as someone once put it so well) who develop such extra features are kinda waiting for the next firmware so they have a way to unbrick their devices when they inevitably make a mistake in their development.
However, there is one bit of good news: the sort by first letter thing is already a standard feature on the 505. When you enter the author or title menu, if you look at the "page" number at the bottom it should show you page 2 of (whatever). Hit the "page back" button and you see the by letter break-down. As I recall, it's not a full 26 letter break-down, but rather an A-C type of thing. That should still help some with 4k books.
