The tickets state that the concert is at 7 o'clock. Does it actually start at 7 or do the doors open at 7?

Not all concerts start at the same time. If the ticket says the concert is at 7pm, the doors will open at 6pm.

Gate opens 1 hour prior to start time. They have always started on time at all the shows I've been to.

Doors opened at 6

If it says 7:00, then that's when your opening act will start

Someone will start playing at 7. I think you can get in as early as 6.

I'm assuming its the same for every concert, but if it says 7:00 on the ticket the doors should open at least an hour before that.

I believe the doors open at 6. The opener playing tonight was on before seven. Headliner normally won't go on before 8:30.