Refreshing the bottom paint on a sailboat is part of the regular maintenance schedule. For trailer sailors, or people who dry store for the winter, an "ablative" type paint is the usual choice. Usually done in the spring just before launching for the season. This type of anti fouling paint works by slowing eroding as the boat moves through the water. It's effectiveness is not diminished by air and sun. For boats that are left it the water year round.... a hard shell paint is commonly used. This type emits anti fouling biocides and doesn't require the boat to be moving to work. The hard shell paints... some are classified as "modified epoxies" do not maintain their properties when left out of the water for extended periods because the anti fouling chemicals are leeched out by the elements.
Applying bottom paint is pretty easy... on a trailered 22 footer you should have no problem tackling the job on your own... if you want. You can read up on this stuff by going to the West Marine Advisor. One gallon of paint should be plenty to apply two coats and an extra layer on the front of the keel and rudder. From what I can see, your boat's bottom looks petty decent... so perhaps a power wash and some light sanding to get the grit off... and you can just roll the new right over the old.
Topside painting is a completely different endeavor, not really normal maintenance..more like restoration... lots of prep, lots of time, expensive paint. As recommended by others, buffing and waxing will most likely get your boat looking sharp.
