If you're unsure about fit, [MENTION=403926]Rsmith11[/MENTION], stand over the top tube with both feet planted on the ground. You should have about an inch of clearance under your legs. Since you're 6'3", I would guess this bike is in the right ballpark for you.

As for rehabbing it, look for a bike co-op in your area. They have all the tools you will need for a small fee, and will teach you how to do repairs.

As others have said, you got an incredible deal on this. Schwinn spec'd this very well. Mrs. Trotsky has a Super Sport from that year (very similar frame with 600), and it's an incredible rider.