If your offsite you willl park in the parking lot at MK and have to use either the ferry boat or a monorail to get to the front of MK. You can use the monorail to go to any of the resorts it goes to. You could also use a monorail to go to EPCOT from the TTC(parking lot at MK)
TTC means Transportaion and ticket center.
MGM and AK you will park in the lot and take a small tram to the enterance.
From MGM you can take the boat that stops at the Boardwalk and Beach Club areas and goes to the International Gateway to EPCOT. They do not check id's for any of these.
So yes you can and will have to use some of them to get to where your going.
Lori