I have a water base stained wooden fence around my pool. The stain is at least five years old and mostly gone. I want to replace the wood panels with vinyl and paint the posts and cross members white. The wood to be painted is very dry. Is any good

Using primer over a dark color. How should it look?

I want to paint the interior of my house. For each wall, I want to use different shades of the same colour. Please advise.