I can't help much with restoring, but there are lots of board members here who can direct you to some great links on how to do it (like Muv's). I have a 15-31 (a $20 garage sale find) that I've cleaned up, and I need to get to work on Gramma's 66 treadle (it's in bad shape like your featherweight). And I have Aunt Sandi's featherweight that is in great condition.
Anyway Good Luck and have fun with it!