Zune and audio book compatibility

I understand that the Zune is not compatible with Audible file formats. With this in mind...

1. Are there ANY audio book formats that Zune is currently compatible with or that can be recommended

2. Would like to see a bookmarking feature included in Zune software.

3. Are there plans for a Zune forum

4. What is the process to log an enhancement request for Zune features

thx