We're at OKW now and the pools close at 10 but I'm not so sure that they actually lock the gates. Less likely at the quiet pools anyhow. If I remember, I'll take a walk tonight and check.
Yes, the grills are located near the quiet pools. They are charcoal grills similar to the ones used in public parks. I hope the weather is good for you to grill. January can be very cold at Disney, even if the temperature is in the 40s, with wind and humidity, it can feel much, much colder.