We did this for the first time, a few weeks ago in September. I had the same questions.
We had 825 res. We got there a little after 8 to allow for the parking. You will get parking right up front, first row, since its early, before regular parking even starts. There were no yellow suited parking attendants when we went. We parked first row, fifth spot and walked to the transportation stations. We took the monorail, and it did stop. First run, brake testing. That delayed us about 10 minutes. When we got to the gates, there is a "Reservations" gate off to the right. ( although it may be a rotating location ). We told the gate attendant we has reservations, showed or room card and we were in. She didn't check a list, or actually look at our cards very closely, which led me to wonder if its just that easy to get in before the park actually opens. It was awesome to be on main Street at 820am and there was barely ( maybe 10 people ) there. We got great photos of empty Main St, the castle with nobody in front and an awesome shot of the train station, entry. ( which I use as my desktop now!
Have fun, enjoy the breakfast, it was very good!