DVD Decrypter is free.
Download from
http://www.digitalFAQ.com/forum/dvd-...-download.html
No, you cannot use Premiere. It will re-encode. It's not needed anyway. You don't need a video editor at all.
Encore is too fidgety. It has narrow understandings of MPEG, even when they're within the spec. Pros don't use that, nor do hobbyists. You can try it, but don't be surprised if it rejects your sources.
There's really not any free DVD authoring software. At least nothing easy and straight-forward. The free stuff is all very amateur hackish, usually with no DVD menus as as option. PM me about this, I have some more ideas.