I think what the 3 yo needs are some playmates his own age. Are you looking to getting any more children his age? 2-4yrs? This will help tremendously in keeping him occupied when he has a friend to play 'with'.

As for the menu, I have an 8 month old of my own with all the other daycare kids, and she does not eat much the same as them. Still on simple foods where the older kids can handle pb and j sandwiches, my baby cannot yet have that so its a different meal for her. Most pastas should be good for both kids to enjoy, just cut up tiny for the baby. 3 yr olds probably prefer plain pasta without the sauce. I serve my pickier kids penne with butter and parmensan and they gobble it up! Also you could try serving brown beans, most kids love beans and so does my baby, mashed of course. With bread and butter, and kernel corn, a pickle and some fruit to make it a meal.

Where you are just starting out, you may need to put your foot down on the behaviour this kid is displaying at your house. Not listening to me when I ask you to do something (or NOT to do something) would result in a time out. Although he may not talk much, he understands fully what you are asking of him.

For the next time he refuses to walk, dont make him make you feel like a fool. I never feel badly about disiplining my kids, or daycare kids in public. Consistency is key,. if they know they can get away with stuff outside the home, say goodbye to any more walks without issues! A firm hand on the wrist may make him pick up his feet. He cannot control your daily schedule, and if it is walk time, then he will walk! Maybe a time out after you get back just to make sure its not okay to pull that kind of stuff.