End of year party

I'm giving some thought to letting my kids have a little end of the year party at the house. My younger one is finishing kindergarten, my older one is finishing fourth. I would guess it would be around 12-15 kids.
Their last two days of school are half days and I was thinking of doing a lunch party after school. I'm thinking just hot dogs and hamburgers, assorted chips, juice boxes and water. Then I'll have ice pops, fruit kabobs and let the kids decorate their own cupcakes for dessert.
I will invite any of the moms who are available to stay also. Should I have additional food for them on top of the hot dogs and hamburgers? Grilled chicken? Maybe a big salad and/or a pasta salad? I'll probably also get beer and wine.
As for activities, should I just let the kids make their own fun in the backyard? Or should I plan stuff? We have a small play structure and soccer goals in the yard. The older boys usually just play sports when they're over. For the younger ones, I was thinking maybe a few things of bubbles, some beach balls, and maybe water balloons. I could also set up a sprinkler and slip and slide if it's hot.
What do you think? Am I missing anything?

Re: End of year party

That sounds awesome! Can I come? Lol

Enjoy it!! I'm sure all the kids will have a great time!
Excellent summer kickoff!