How hard is cleanup in order to keep things usable? I love the idea of painting minis and models- especially learning the various weathering effects but it seemed like it would take a lot of energy to keep everything functional.

Trivial, honestly. And I'm not a particularly disciplined or functional person. The overwhelming majority of hobbyists use acrylic, which has no meaningful smell and can be thinned with a drop of water. I haven't had any issues with staining or the paint going where it's unwanted, and you typically only use a few drops at a time.

Sometimes I use a dry palette and sometimes a wet palette. The dry palettes are plastic and cheap on Amazon. You rinse them off in the sink. If the paint dries, use a greenie or a brush - no problem. The wet palette just needs to be wiped off with a wet napkin before you close it up, and to have the wax paper replaced when it starts to rub through. If you get the sponge dirty, it's a sponge - just fill it up with water, squish it, maybe use a little Mean Green/Simple Green/etc to clean it up.

The airbrush is a little more involved, but I dramatically overestimated how much of a pain in the ass it would be. Most of the time the cleanup for that is 3-5 minutes and not unpleasant. Occasionally it'll need to be broken down a little further, but it's still not a big deal. The mechanism isn't nearly as complex as it may initially seem.

Brushes aren't a big deal to keep clean. You'd destroy a bunch, but you'll learn over time what not to do. Just don't start with the (comparatively expensive and arguably barbaric) sable brushes, start with garbage quality brushes and treat them as disposable. Rinse them, use a little brush soap, and don't brutalize or drown them and they'll last longer and longer and maintain a better quality, then you can upgrade.

Nothing else really comes to mind in terms of labor.