Another Vegas/DVD architect user here.
I use pro version, because it has GPU acceleration, but other than that, premium version (~$100) mentioned by Mr. Blue1 has all the basic tools and plue DVD Architect.
In Vegas, you import media files, such as the source video clips and audio files into a kind of 'preparation pallette'. Then, drag & drom these souce materials to tracks, pretty much like DAW. You can cross-fade, and use envelope to fade in/out video clips as well as audio. You could have multiple video and audio tracks, and actually use 'plugins' to do add some effects. In fact, I use quiete often color correction, white balance correction, and brightness/contrast correction, when the shooting was not optimal.
Then you 'render' to a single video clip file (or video/audio separate format), but this step requires patience, if the video is full HD, and long. But, with patience, you can get pretty basic title, fade in/out, cross-fade, background music, etc. If you like you can EQ/comp the audio track as well.
DVD Architect has a basic template for DVD authoring, such as basic background and typical submenu creation. I just use the basic one, and use large buttons and arrows so the viewer can navigate easily. Of course, it takes care of the final step, which is burning to the disks.