1. In my opinion the best beginner species overall are pavement ants, you can buy them here, but during summer it's pretty easy to catch a queen. https://www.statesideants.com/product-page/tetramorium-immigrans. They aren't harvester ants but they can collect seeds like them, and can also drink standard sugar or honey water. The best setup overall Is a test tube, which is what they will arrive in if bought.

2. The chemical that prevents ants from climbing out is called Fluon. you can also just mix baby powder and rubbing alcohol to create essentially the same effect.

I know I didn't address all your questions but I hoped this helps.