Hey, congrats w/ the find, and welcome aboard! You made a great choice and got a good deal to boot! Nice Christmas present.
I would try a cleaner wax on the rudders, or a plastic polish. It may work to remove the mildew. Maybe some wet 600 grit sandpaper, then follow up w/ plastic polish or wax. It wont hurt anyway.
You will hear alot of people tell you that you don't need to wax poly hulls like on the Wave, but I do for the following reasons: I use the wax as a cleaner, it does a great job removing stains and makes future cleaning much easier. Poly is slightly porous, so some wax remains in those pores, minimizing dirt collection. It adds a little exra sheen as well. So, wax away. You will find that annoying rain streaks wash off much easier.
As far as graphics, like sunjammers mentioned, you might replace them, or just strip them off and go for the 'clean' look. Getting new graphics to stick on an older boat may be tricky. Decals don't stick to poly real well.
Have fun w/ your new toy!