[otrs] Restoring an OTRS from a prior version?

I'm currently running OTRS 1.2.3 and I do daily backups of OTRS using the backup.sh script. This produces a .tar.bz2 file of about 113KB. Can I use this to restore all of my OTRS for when I rebuild on a new server with version 1.3.2? Basically, does the restore.sh script only restore the system aspect of OTRS? What all does the backup.sh script backup? I'm also wondering if I can directly copy in my Custom OTRS Theme on version 1.3.2? I've backed up the Output directory in 1.2.3 and I'm wondering if it's that easy? thanks marshall