Fahr, paint thinner, gasoline if you don't mind smell and on hands, or Brakleen is real clean. Brakleen doesn't last long per can, may take several. I would use that after scraping and wiping as much off as possible.
Far as the seals, they are in the back of the hub you took off to look at brakes. That is I assumed you did it that way. I know some drums come off w/out hub, but hard to do those, too rusty usually. If not, you need to pull the little cover off the end of hub, remove the two nuts in there after bending lock tabs back out of slots, pull off whole hub. The seal is in back, right next to bearing! Try not to let the hub set on new seal when installing and roll out the spring or damage in some way. YOu have to regrease the bearings after cleaning and putting in new seal. the bearings are lubed by the rear end oil, but need some grease to start with when cleaned, serviced. YOu also need to get a shop manual and READ it. This is all in there.
