Is FLAC something I'd need to download elsewhere?
I don't think so. I think you can just click "Export" under "File", then enter any metadata you might want (you don't have to), click "Okay", and then select "FLAC Files" from the "Format:" drop-down menu at the bottom of the Save As window. If "FLAC" isn't one of the options, you might have to go to "Import / Export" in the preferences, and click the "Download" button next to "FFmpeg library" before doing the other stuff. But I don't think you need to do that for FLAC.
Also, since the recordings I'm doing are live, is it tougher to "mark" the songs?
You can always select each song and click "Export Selection" under File (instead of Export). That way you'd get separate files for each song. Within an Audacity project, you can create a "label track" that marks each song, but I'm not sure if there's any way to embed that into an exported file. I'll leave that question for others on the forum.
Lastly, maybe you can help w/ the other question I posted-- regarding freezing when I try adding effects. (in this case, EQ)
This is Audacity's standard, built-in EQ effect? If so, I don't think I have the knowledge to help; you'll have to wait for someone else. If it's a nyquist plug-in you're using, though, I'd recommend selecting shorter bits at a time.
--Allen