If you don't mind spending some $ on paint, the Nelson paints are extremely light and easy to use since they're waterbased. Being so much lighter means you can mess up some. (great for inexperienced painters!) Read the instructions, it doesn't spray like regular paint.
Be careful with fillers. What you can use will depend on your paint choice. I've seen guys use lightweight spackle, but that doesn't seem like a good choice for waterbased paints. If it's not large dings, pick up some of the red glaze in a tube from the auto parts store. It's heavy, but impervious to most stuff. Use it sparingly.
Fill holes by cutting a piece of balsa the same size and thickness as the hole and glue in place. If you have access to the backside, a backer will make it much easier to get it straight. In a pinch, you can stick your patch to a piece of tape to hold it in place.

Here's the paint gun I use: http://www.harborfreight.com/cpi/cta...emnumber=92126

Here's the paint I use: http://www.nelsonhobby.com/paint.html