10 ft still consider high bro, typically plaster ceiling will eat up 6inch or more, my ceiling is 11ft, after plaster ceiling is about 10 ft 5inch, for my living room, it will be lower because I wan cover some beam with cornice, so it is about 9ft 8inch like that
Nope, gypsum board is gypsum board, plaster ceiling board is mixture of chou gan + plaster powder.