Womble's MPEG Video Wizard _could_ do most of the things you're talking about there - but it's only really designed for cutting/inserting scenes.

If you do want to go ahead and make image changes, and even make decent audio changes I'd recommend demuxing the VOBS to M2V, and then using DVD2AVI and AVIsynth to edit them in something like Premiere.

I've got a link to a really good step-by-step guide that I'm using to make my prequel edits - but I'm at work at the mo and don't have it here.