Does this place have a playground on the campground? And are there grills/grate over the weird concrete fire things? Or is is recommended to bring a whole grill to cook on?

No grates but 2 playgrounds, nature trails and good biking for the kids. There is plenty of standing water, so plan on mosquitoes for the season.

Does it have cabins

Yes, there are two playgrounds. No, grills are not provided

Yes

Yes the campground has at least 2 playgrounds by the shower houses and the fire rings do not have grates you could bring a whole grill to cook on or I just recommend a tripod grate that can go over the fire.