I have an 88 Cajun Maverick. This may seem a silly question, but I'm basically a catch and release guy, and have never used the livewell. But if I do use it, I want to make sure I'm doing it right. The livewell switch seems to run an aerator (pumping water through a CPVC pipe with holes). There is an overflow drain, and a drain with plug in the bottom of the well. What's the procedure? Do I leave it plugged, and simply run the aerator and let it overflow out? I have forgotten to plug it and it filled up of course, but didn't cause any problems (didn't overflow the deck or anything).

Leave the bottom drain plugged and circulate the water on a timer function if you have one, if not do it manually from time to time. low oxygen in water will result in dead fish so aerate often. Ammonia(pee) kills fish so circulate regularly. In hot weather this is even more important.  Quick change in water temp will also kill fish I do not ever add ice, however I have heard of people doing so.

https://www.bassresource.com/bass-fishing-videos/fish-care-in-the-livewell.html