High-def AVC discs can only be played on BluRay players, even if you burn them to DVDs. You can't create a hi-def DVD that will play on your DVD player.
Right - I've been using corel dvd movie factory 7 for about 5 years to make my avchd disks for my bluray player, but I got a new camera and decided to bite the bullet and figure out how to do it using DVDA. Apparently not as easy as I had expected.
Sorry, 29.97p is not included in either the DVD or BluRay official spec.
Just render as 29.97i in Vegas for DVDA, and all should be fine. Others have had great results with that method.
The DVD spec is unlikely to change at this point, however there are hints that 30p will be included in the next revision of the BluRay specification.
BluRay does allow 60p (59.94 progressive) at 1280x720 resolution.