This thread is from 2009, but is actually asking the same question you are.
http://www.disboards.com/threads/ecv-and-the-treehouse-villas.2085067/
The answers were that:
- there is a utility room, which houses the water heater and plumbing access, which is locked (so no access there).
- although you can park under the treehouse, since there is no protected place to park the
ECV, you would need a tarp or a grill cover was also suggested to cover it. (I have seen other things confirming you can park underneath )
- there is an outlet on the porch and one on the pedistal that the treehouse rests on. The tree houses were not complete yet when that thread was written, and no one was sure whether a cord would reach to plug in
- it is (or at least was) possible to rent
ECVs which had batteries that could be removed for charging. If you have a vehicle, the ECV could be left in it and just the batteries brought in for charging.
I have not heard or seen anything about a fold out ramp. I can't imagine that working the way the units are constructed and how high off the ground they are. As far as I know, only the 4 handicap accessible Treehouses have ramps.