If can, pls use Maxilite as undercoat before paint.
then, 5L for each bedroom, toilets need 2L.
Wooden door frame buy 2L will do.
Grille remember to buy paint for car use (steel paint), better.

1. Maxilite buy big tank RM60++ only, sufficient for ceiling as well.
2. 5L Jotun around RM90 (if u buy at Sri Petaling), other place maybe charge around RM110. If you want cheap, buy all one shot ask for discount.

Jotun is good.