DelMarVa is a nice place to ride. For your first tour, I'd go the credit-card route, especially since campgrounds are terribly prevalent where you are headed. Worry about one thing at a time: first get a feel for touring, then add the camping part in. Downside of motels, at least in summer, is that you often need to make reservations, which really detracts from the free-spiritedness of bike touring. If you go in the fall you probably don't have to worry about it so much.

And, you're right about the winds there, they can be brutal. As long as you are mentally prepared, though, you should be fine.

I second the "take more water" advice, especially in area like DelMarVa that is often lacking in shade, gets lots of sun, and can be very rural. Don't count on knocking on doors to get water. I love the Zefal "Magnum" water bottles that hold a liter and fit in regular bottle cages. Two of those and you have a half gallon! Also, stash another quart bottle of water in a pannier just in case. Or, at least, have an empty bottle available that you can fill if the area is looking pretty desolate.