#1 The MPEG2 file is 3.8MB so no problem there
#2 Not sure what you mean by ‘DVD Compliant’. Shouldn’t rendering out of Vegas to, MPEG2 (PAL Widescreen DVD Architect Stream template),already be compliant?.
#3 I think this may be the issue. I didn’t render a second audio file to AC3 as the audio came with the render into Architect. What confuses is me is that advice from here, and other places, suggest rendering once for video and again, with exactly same file name, to AC3 and Architect will automatically find the AC3 file. Will the original audio then be replaced by the AC3 audio in Architect?.