3' by 3' area is three feet by three feet. It's just a common area to do work in. Once you get doing it, you can adjust this to what works best for you.

A polish is slightly abrassive--technically. You use a polish before a wax to take out fine swirls and other imperfection. Polishes also increase depth and shine before waxing.

Some companies (Zaino and others) choose to use the name "Polish" on their wax. I really don't know, maybe they think it sounds more sophisticated then "wax." In reality, Zaino isn't wax, it's a sealant. Sealants are synthetic polymer protectants that serve the same function of wax but last much longer.

Mothers uses the name "sealant" for glaze. A glaze is really a oily filler that you put on after polishing but before waxing. You wouldn't use a glaze before a sealant because as a rule of thumb, a sealant bonds best to a clean, non-oily surface.

See how the lines are blurred? 9 times out of 10 a polish will be a varying abrassive product, a wax will be a carnauba, and a sealant will be synthetic. Forget about glazes, you don't need them and they don't last long.