I am trying to make my first DVD from Sony Vegas Pro 8.0

I have downloaded the most recent trial version of DVDa 5.2

here are my questions:

1 If I have a file size of 1280x720 do i need to re render it at 720x480 before bringing it into DVDa? I am rendering the file i bring into DVDa as an AVI file is the correct?

2 When i open DVDa I can see themes in the THEMES window...I select File>New>Single Movie>(MPEG-2 720x480-60i, 16:9 NTSC) then when i select my video file the Themes window says "No themes available"

3 In preview the video is there and the chapter markers are working but there is like 1/8" of letter boxing on both sides of the video

Do I have my settings goofed up or what?

1. Yes to a re-render if this is not Blu-ray.
Ideally, using the appropriate templates, you render two files, MPEG-2 for video and AC-3 for audio.

2. A "Single Movie" doesn't have a theme.

3. Correct #1 and this should go away.

I highly recommend reading Vol. 1 Issue #7 (http://www.jetdv.com/vegas/forum/viewforum.php?f=5&sid=2d60014512353caa84527e58374d0acd) of Edward Troxel's free newsletters as this issue deals with this exact topic.
While written for earlier versions of Vegas and DVDA, everything is still applicable.

Thanks. Printing the newsletter now