Can I buy paint tint to mix with my base paint for interior walls?

Do I need to prime a flat paint before repainting with an egg shell or satin… also in the bathroom do I need a different type of paint?

I primed my steel siding with Epoxy Primer. Can I topcoat it with acrylic latex?

Our house was built in 1911 and have lived in it for 1&1/2 years. The dining room has a beamed ceiling and just noticed for the first time 5 or 6 circular and hollow tan/brownish spots on the wood beams. About the size of a half dollar. The tan coloring

I am going to paint my new house. First I want to paint the exterior. Before painting shall I wash the exterior portion? After that, what is my first step to paint the exterior? Please tell me.