^ Yes, don't worry about driving at the 'right' side of the road. Driving in the Usa is very relaxing and easy. From my personal experience I can say that I was already used to driving at the left side of the road after being 5 to 10 minutes on the roads in the UK.
About the parks, you can go to CP (& KI) and then drive east to SFGAdv. In between you then can visit Kennywood, Hershey, Knoebels & Dorney. From SFGAdv you then can go further South and visit BGE, KD & SFA and fly back from DC. Or you can go North from SFGAdv passing New York and visit SFNE & Lake Compounce and fly back from Boston (or NY).
Comfort Inn has a handy search function for hotels near themeparks on their website.