NTSC DVD is always 720×480 MPEG-2 format. In Premiere, Export to Adobe Media Encoder and choose “MPEG-2 for DVD” and then pick an “NTSC Widescreen” preset, and normally using 29.97 frames. This will generate the proper files that you can use in Adobe Encore to create the DVD.
You can also export from Premiere directly into Encore, not a workflow I use so not sure on the path to go there. File > Dynamic Link > Encore maybe?
Jeff Pulera
Safe Harbor