The Disney area isn't really bicycle-friendly. A few of the resorts have places where you can rent bicycles (two-person, four-person, etc.), but that's about it. I recall reading somewhere that bicycles aren't allowed in the apartment complexes. There's really not much you can do with one. I suppose if you're at Chatham you could ride your bicycle to Publix for groceries or something. But it's not like you can just bike to work or anything. Everything is too far away and there aren't that many sidewalks. The only time I rode a bicycle was backstage at Animal Kingdom. They have these sweet, old-school, blue Schwinns (other parks used to have them, but due to misuse, they've all been taken away except the DAKcycles). But yeah, it's not worth bringing a bike. I don't know about rollerblading/skateboarding. I expect there'd be the possibility of the former in some places.
There are plenty of places to walk/run for exercise, especially around the Chatham/Commons area. If you like to walk, just walk around the parks. The World Showcase Lagoon has a circumference of about two miles. A few times around that and you've burned quite a few calories. There's a nice walking path that takes you from Epcot to The Studios. It's really easy to find places to walk, and it's much more fun than a treadmill or walking around where there aren't any people.
Regarding Roll Hoppers (this is from
http://www.wdwcollegeprogram.com/sap/its/mimes/zh_wdwcp/students/role_descr/onstage.html):
Hopper
Cast Members in this role may experience more than one working environment. These Cast Members will rotate to different locations within the same line of business, or they may be able to experience more than one role at the
Walt Disney World Resort. Independence, flexibility and a willingness to work with different teams and leaders are important skills to have in this role.
Hopper Cast Members may be working in any one of the roles explained in this list and should have selected all of the following opportunities on the Role Checklist:
* Quick-Service Food and Beverage
* Merchandise
* Operations
* Custodial
* Recreation
* Transportation
* Full Service Food and Beverage.
Responsibilities may include: working in multiple locations across the Walt Disney World Resort, including all four theme parks, two water parks,
Downtown Disney® area, Disney's Wide World of Sports® complex and any of our resorts. Some areas may require heavy lifting, bending, standing for extended periods, and working outdoors.
So on your Roll Checklist, select that option as well as all the secondary options.
I can't answer the one about classes; I didn't take any.
Poor Animal Kingdom was WRECKED after Charlie. 
