What kind of paint do you use on metal chairs?

It's best to paint on dry clay only. For wet clay, you'll need a glaze, which is more complicated and doesn't work on air dry clay.

No. If you put the mug in the dishwasher, there is a high probability the paint will come off.

You can use acrylic but you will not get the best results. The acrylic paint will harden the shirt and likely come off in the wash.

You can typically find primer and paint that are specifically made for tile at a paint store.

Depending on the look you're going for, you can use chalk paint or spray paint for best results.

Yes, many barbers/hairstylists rent their chairs in salons/shops.