Help, new 9-3 Aero owner, have some issues

[JimmyJam]

Just bought a '55 Aero Convertible. 3 problems....stereo is blowing a fuse and won't last more than 5 mins. Is this common, any easy remedies bearing in mind I'm not a spark!
2 warning messages on dash fir self levelling lights not working and seat lock broken, big too fussed about these issues but would like to at least get rid of the messages.
This is my first Saab having come from Alfa's do I'm used to electrical niggles but the stereo prob is a PITA!
Cheers

[JimmyJam]

Thanks