The batch rendering in Vegas is more for rendering multiple formats of rthe same material and goes like this:
Go to Tools > Scripting> Batch Render, and a dialog box will pop up. The main trick here is NOT to check on one of the unexpaneded options (e.g. Mpeg 2). First expand the categories and check what you need.
You can choose to render the project, selection or regions. If you set up your different sections as regions, you can probably get where you are going.
In Excalibur, the Asset Collector has more options such as render BOTH the whole project and regions in the same or different formats as well as grabbing still images for you.
Gary