Hi, Mary!
We rarely have a vehicle when we travel to Walt Disney World. Thankfully, you don't need one!
Regarding transportation, you'll have no problem taking resort transportation between Disney's Yacht Club Resort and Magic Kingdom Park. You'll take the bus for this purpose. Check out the
Transportation page on Walt Disney World.com for information on how to get from your resort to any other location in Walt Disney World.
Regarding temperature in March, the average low is 56 degrees, and the average high is 78 degrees, according to Weather.com. I've been to WDW several times in March, and I can tell you that the pools will be open, heated and LOVELY; definitely bring your swimsuits! (Don't forget that the hot tubs are open as well!)
Have a wonderful vacation in Walt Disney World in March! Please send the Panel any additional questions you may have as you think of them. We love to help!