I think in most cases, you want to choose “All Regions” and “CD Tracks”. If you have gaps between the Track End and Track Start marker, check out the Render Options to make sure the time between the markers gets included somewhere so you have the proper song spacing when you render separate WAV files.
If you use CD Track Splice Makers only, there is no need to worry as all the time will be included in the proper CD track.
CD Track Groups is something I helped push for so we have a good way to render vinyl and cassette pre-masters. Side A of the vinyl can be set to CD track group A, and side B of the vinyl can be set to CD Track Group B. Then you can render a single WAV of the entire album side/CD Track Group and also produce a report that matches the rendered audio file for each side. Before the CD Track Group was added, the times for side B (and C, D etc.) would not make sense because the audio file obviously starts at 0:00 but the report would start the times as they are on the timeline.