J.B.
Hello, I am a mother of two and my son had his 4th birthday party last summer. I think that anytime you say cake, the kids are going to go crazy. I would suggest doing the cake towards the beginning of the party only because of the time of day that you're having it. You should not feel like you need to feed them dinner too. So if you did the cake at around 3:30 or 4:00, then they would be fine until the party is over, and you wouldn't be completely spoiling their appetites for dinner when they get home. I also wouldn't worry about doing other snacks unless you really want to. Parents know that when they send their child to a party, they are going to get cake and icecream and that's all, unless you specified a meal on the invite. Don't go to overboard with all the planning a food, I have really found out that simplicity works the very best when planning a little child's party. Good Luck and Have fun.
J. B