RE: How old should the little guy be?
I think you should take them out and I would take both at the same time. They will keep one another entertained when the action is slow. Just remember to ensure they have fun. My daughter came with me a time or two when she was 3 and then tracked her first deer (I did the shooting) at age 4 with a flash light and impressed the stew out of me. She has been a great hunting partner and took her first deer last year just before her 11th birthday. My son will soon be 4 and has made serveral trips with us over the past two seasons. I only hunt a few days each year without at least oen of them and that is fine by me. They are only young once.