I bring meals/snacks to long classes when I know I'm not going to get a decent break. So long as it's not a lab, that should help. Eating right before and after sometimes works too.

If you don't think you can take on a second job along with your teaching and school, then I wouldn't do it. Is there some way your brother can force your hand on this, or is he just pushy and invasive? If he's that bad, then I'd be tempted to just not tell him.

It sounds like you're doing quite a bit of planning around your schedule already. The thing with your AA group sucks. I guess the upside is that it's only a sure thing for 3.5 months and after that you might be able to go back. Maybe after things get sorted a little better, it won't feel quite so overwhelming? Definitely keep that time in for yourself. It sounds important to you managing things. Part of dealing with high stress and a lot of responsibility is taking time out for yourself.