Is there a grill already there

Yes. But for larger groups they will have you purchase a permit. Check with Dept of Recreations

There are some small charcoal grills in the pond area. I think you can also request portable grills for larger groups when you're there. You have to bring your own grilling tools.

They have a childrens park fenced in and an ausom dog park too.

Yes it's a great family place

Adding onto what Rick said, you have to bring your own charcoal, starter fluid/fire starter(s), utensils (cooking/eating), and anything else you want. But, I do advise you to bring some heavy-duty or grilling aluminum foil: as they do not clean the grill tops.