In answer to your questions:
1. You can create multiple ad packages for the user to select from with the relevant price and time frame set on them as you can see from the settings on the
ClassiPress admin demo.
2. As above, yes, based on different ad packages created by you.
3. Uploading mp3 files is not a default option of the theme and would require customization on your part.
The image used in the
user profile is linked to their email address/gravatar.com account. Thanks.