The MK parking lot does not "close". If you are there very early there are no CM's there, you just proceed through (There will be a sign that says Welcome to the Magic Kingdom please proceed to your destination). If you are there anytime after 7am the CM's are usually there.
you can get into the parking lot at the T&TC no problem...Im not sure if the monorail starts running from the T&TC early enough for you to get to you PS in time though....I would call and ask what time the monorail starts running from the T&TC on the date in question...one thing you might consider is walking over to the contemperory resort and taking the resort monorail to MK....
The monorail does run early enough for PS at MK. You just have to have your PS number as the CM's at the monorail will ask for it (they have a list) and then they will assist you in getting to MK's front entrance in time for your ressies.
The Castmembers at the toll booths usually arrive about 1 1/2 hours prior to park opening time, however, as Liberty Belle pointed out, there is always one open lane into the parking lot. So don't worry, you will get to your breakfast in time.