Hello Zauchuexue84
To avoid backtracking, it would make more sense to travel Paris - Basel SBB - Bern - Interlaken Ost - Luzern - Zurich - Munich. The places you plan to visit are all connected by direct trains (Paris-Basel / Basel - Interlaken Ost / Interlaken Ost - Luzern / Luzern - Zurich HB / Zurich HB - Munich).
A 3 days Swiss Travel Pass is certainly a valid option, it all depends on what you plan to do… Yes, it is refundable for a fee.
3 days is rather insufficient to see our country; you might be able to get a glimpsy, though.
Kind regards,
Roland