great you are taking your 7 yr old with ya. I think my brother in law is going to start is youngest (7 also) this year, and my brother start both his boys very young.

I would personaly take both an shotgun and an 22, (which I have done in the past)

but if you can't affard both, the ruger 10/22, you'll have a good little squirrel gun, plinker, and an gun you can mod.