For your early ADR's you can get through security, but they won't let you into the park to walk to CP until 7:45am. The character breakfasts gates are to the far right side of the entrance gates.
Even if you don't have an 805am ressie, check-in as soon as you arrive. We had an 815am ressie, checked in as soon as we arrived at CP and wound up being seated right at 805 when they opened. We were the 5th family seated, got into the buffet lines with no wait, and pretty much got to eat most of our food before the characters started coming through.
One piece of advice if you want to attempt to make rope drop: take care of your check as early as you can during your meal. This way you don't have to wait at the end of your meal. We didn't make rope drop despite being finished with our food and characters by 845am because we had to take care of the bill, which took forever, especially when you are on the dining plan dealing with multiple checks for the meal and tips. We didn't make it out of there until a few minutes after 9am, but still managed to get on Dumbo without much wait!
Have fun!