Hi Nicholas,
Hooray for staying at
Disney's Yacht Club Resort! This is one of my family's favorite locations for vacation. We love being close to Epcot and Disney's Hollywood Studios and the pool is fabulous!
Disney transportation starts one hour before a park opens. This means if Magic Kingdom opens at 9:00 am, the buses, monorail and boats will begin at 8:00 am. If Magic Kingdom has an 8:00 am opening, you can hop on the bus to the Magic Kingdom and either walk or take the monorail to Disney's Contemporary Resort to have breakfast at Chef Mickey's. If Magic Kingdom opens later, there should be a special bus to take you to your breakfast reservation. You can confirm that with concierge the day before.
You will not have the option to walk through Epcot to get to the monorails as the park would not open in time for an 8:00 am breakfast. In addition, you would need to make sure you had the park hopper option if you were not planning on going to Epcot for the day or you would lose another days admission if you were going to Magic Kingdom after breakfast.
While you can drive to Disney's Contemporary Resort for breakfast and park there, you would need to move your car to the Magic Kingdom parking lot. Parking at resorts is for guests of the resorts and those dining at a restaurant.
Wishing you a magical vacation!
Beth