Hi Debbie,
How wonderful to have so many days to explore the 'Greatest Place on Earth'!
You will be able to purchase a 'length of stay' stay pass with your resort booking (call 407-WDISNEY). This will be good from the morning of the day of your arrival until the end of the day on the day you leave. Your tickets are put right onto your 'Key to the World' card, which is also your room key and charge card (if you want charging privileges).
This can be purchased with different
options - 'park hopper' option, 'waterparks and more' option and a 'no expiry' option' (which you won't need if you visit the parks each day). If you think you may want to visit more than one park per day, the 'Park Hopper' option is the way to do it. However, with 13 days at the parks, you may well be able to plan out your visit and not need to visit more than one park per day.
Debbie, have a magical time!