Looking at the razor that rust at the edge is a bad sign. Usually when its that close to the edge it means your going to have to do some major work, probably redo the edge including bevel and all especially if its deep like you say. You'll probably need a 1000 grit hone to do the initial work.

I don't think there is any way to replace the color applied to the blade whether its gold leaf or enamel, well... let me say if you have a really small brush and a really steady hand and some good magnification and can get some jewelers enamel it can be done but I don't know of anyone who has ever done that type of restoration. You might ask Bill Ellis about that one.

I wouldn't assume the scales are plastic. I would assume they are celluloid. You can usually tell if you start to rub hard on them with a cloth celluloid will emit a very characteristic smell. Any heat will do that stuff in. I would try polishing the scales up with something like cape cod polishing cloths or you could use a dremmel but you have to be VERY careful (use a very light touch and move very fast over the surface with a muslin polisher) and you need rouge made for plastic or very tender metals.

Good luck and let us know how it turns out. We expect a razor looking like it was made by the Maestro when you finish. LOL