Your bicycle was made in 1972. Don't worry about rust in the frame - it's rare. I rode my All-Pro in Seattle and in Colorado during winters - the only thing that rusted was the super cheap chrome on the wheels. Just don't leave it in the rain, and dry it off if it gets wet.
One thing that is interesting about your bike is that it uses a pie plate chain protector instead of a regular chain guard, which seems bizarre to me. I know that was standard practice for Iverson, but I didn't think Huffy would stoop to such a cost cutting measure. It definitely makes the bike stand out amongst three speeds though.
As for tires, I think K-mart still carries them in this size (Wal Mart seems to have stopped) they'll cost less than $20 a piece for cheap ones. A bike shop will get you much better tires though. You don't really need anything special, and I don't think they make anything really special in this size anyway.

PS: make sure that handlebar neck isn't about to pop out either. It looks like it's way beyond the minimum insertion mark.