From FEMA I found the flood insurance rate map, for my county, which gave me elevations, reference markers, and zones. This will help my builder / designer determine at what level the first floor of the cabin should be. This search also lead to and erosion control project aerial photo that high and low water marks on the Washington coast by Conner Creek, and close to my cabin site.
The WA Department of Ecology
http://www.ecy.wa.gov/ was able to provide me with the Water Rights Permit number, which will be required when I seek approval for the septic system. Acquiring this information was simple, complete the form, and mail it in. Three days later an email provided the number.
Driveway to home site: The County approved the site plan I created, and the layout for my small driveway. The builder made a request for larger gravel to be used during the construction phase. He suggested that I will want crushed jagged pieces of stone (#3 stones in the trade) because they will compact better to form a seemingly solid surface base to drive trucks on.