People has been telling me to use sealer for plaster ceiling, but I don't know if they are needed. Maybe it is a good idea.

As for the paint for plaster ceiling, Maxilite is the most common. The white color is very nice. Matex is more "yellow" than Maxilite.

You may choose to use Maxilite for the whole house, but my recommendation is to use Nippon 3-in-1 for Kitchen, Bathrooms and Exterior Ceiling (if any)

I am contemplating to use all Nippon 3-in-1 white for my plaster ceiling in my new house, as 3-in-1 is the only paint that is waterproof currently. I have used the 3-in-1 previously in my current kitchen and bathrooms and they are still good after 8 years