I think there are a few threads with specific info on where to stay - my dad is up there, so I don't have to find a hotel/places to eat.
From Whitetop to Damascus is just about all down hill. You really don't have to pedal much - but the grade going the other direction isn't bad (it was a railroad bed). There are LOTS of places that have shuttles from Damascus to White Top (easy ride down). There's plenty of parking in Damascus, if you want to park and ride both ways. Not sure exactly what the mileage is - but I think in the 15 range. Total is about 33.
Anytime of year is Ok - probably best from April - late October. It's beautiful in the fall, but really crowded unless you go during the week.
Let me know if you have more specific questions.
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