1. Use the ID3 tags inside your files to bundle tracks together. Maybe use the Comments field in a creative way?
2. Hmm... Soundcloud integration is neat but a little basic. Not sure there's an app out there that even does what you're asking aside from their www portal itself and maybe their in-house apps.
3. Maybe check the settings on SC -- there are options to default different behaviors. What settings do you have checked in the Airtime config panel?