It shouldn't be any later than 5:00. They have a test or something going on today and if that finishes early they will probably let us in earlier.
Gate is generally open around the clock after that. There is one guard at night and he could be gone occasionally for ten or fifteen minutes. If you get there and the gate is closed with no one around just hang out and he'll be back.
Inside paddock. Limited power (but better last month than I have ever seen it), good showers are across the track.
Lots or people will there, please be courteous with how you set up, park, dogs, children, generators etc.