Welcome aboard! I think the Sunfish is an excellent boat. Our club has 14 of them and the biggest advantage is that parts
and pieces are really easy to find because the design has been around for 55 years. Also they are very easy to rig and unrig. Our students are constantly making the error of putting the boom on the wrong side of the mast
thought so watch out for that one.
There were two types of kickup rudder
designs. One is spring loaded and the more recent. It has many advantages over the old style. If you have the older style I'd recommend changing it but it really isn't necessary unless you do a lot of landing and launchings from the beach.