The Epcot area resorts are closer to Coronado - technically Swan and Dolphin are the closest - but Disney Springs is overall the best hub for getting around to other resorts - aside from busses to all resorts, there are also boats and walking paths to Saratoga Springs, and boats to OKW and Port Orleans French Quarter and Riverside.
There are no reservation restrictions for Disney Transportation to any resorts except for a few times of the year when it can get very crowded - such as happened recently around Easter. These sometimes can pop up around Christmas or New Years as well...usually just for the day or a handful of days.