I think your bike is interesting and worth saving; and as you said, not spending a lot of money in doing so. Now I need to ask if the seat post and stem are stuck. If they are, that is job number one. You should Google "removing rust with oxalic acid" - you'll find a link to BikeForums there. Do not put aluminum in the acid.

The rims appear to be aluminum with rusty plated spokes. I would clean the spokes as best I could (maybe steel wool and WD40, or aluminum foil and white vinegar).

Nice wing nuts on the front wheel.