"What all do you think I would need to get it in a decent shape?"
Start with a complete tear down, cleanup & lube. All you will need is a tub of wheel bearing grease and some time and patience. For the rust, a bottle of Oxalic acid crystals from your local drugstore will mix with water to give you an effective rust removal solution (do a search). You will have a nice tandem cruiser for a minimum investment. Just stay away from hills! Don