I often see pictures of rooms painted with different colors on different walls. I would like to use a dark, rich red color in a basement room but only want one or two walls this color. I would think all the walls this color would make it too dark or

I painted my bedroom and realized after that on the ceiling I still have a couple spots that we spackled but not sanded down and also small dried drips of paint on the walls. Can I still sand and then paint over? What is the best thing to do? Appreciate