Nauti - I thought it was definately family friendly, but my kids are teenagers. I would not hesitate bringing a little one tho. The event is in the park, so if you need to walk away from the water, you can easily do so. With such a little one, I suggest some type of protection from the sun for sure. Also, you may want to set up a little bit away from any PA speakers to keep the little one's ears protected.
I can't give an opinion on the food vendors, as we packed a cooler and brought our own food & drinks. I do recasll a few food vendors being there, so I am sure you can get something to eat. There were several ski equipment vendors there too (but not a ton of them).
My only other thoughts - Bring some fold up chairs or a blanket to sit on, and some sun screen.