I seem to recall that I can render part of the timeline -- since we've done some green screen work in this video, I'd like to get a bit of a preview for how everything is fitting together, without rendering the entire timeline. How do I only render a piece of the timeline and take a look at how it'll appear?
Yes, you can Render part of a Timeline (also Export part of one too), by using the WAB (Work Area Bar). It's located at the top of the Timeline right by the ruler, and has two "bracket" looking end controls. Just drag those to cover your section of the Timeline, and hit Enter.
Here's a look at the WAB: