Zinser 123 is a primer that you could put over that without having to sand first. Then just topcoat with a semi or high gloss latex paint.
Yes, sand first or the paint will not stick, use a primer then paint, you are good to go … You could spray paint them but may get spendy if there are several as in more than 7 or 8 good luck.
Use TSP/90 Heavy Duty Cleaner. Sanding is quite the chore. TSP cleans & prepares surfaces for repainting.