1. How can I get rid of the ads ?
Make a donation (any amount) and the ads will be gone.

2. What audio formats are supported ?

3. Are audible.com .aa files supported
No, its a proprietary format, but if you can find me a specification or some source code, I'll definitely give it a try. 

4. Are .m4b files supported
No, not right now since it uses Andriods media-scanner which doesn't recognize .m4b. It has been reported that
renaming the files to .m4a is all thats needed.

5. It plays my files out of order
The player sorts the tracks on the id3-track number, secondary on track title and third on filename (since 1.7)

6. Where can I download audiobooks ?
For free books check:
  (If you have another great source please send me an email at fredrik.markstrom@gmail.com)

For non-free books I recomend Amazon or anyone selling DRM-free audiobooks prefereably in mp3-format.