You can either stay overnight at the venue (75 twin bunk beds or camping on the meadow), get an official campsite at the state park, stay in one of the cabins on the state park (if they are available), or look into hotels / AirBnb's in Sublimity, Silverton or Salem.
The address is Silver Falls Hwy SE, Silverton, OR 97381. Once you're in the state park, follow signs for Davidson Ranch. Parking is limited, so please carpool! There is also ample parking in the state park where you can leave your car, from there, you can all cram into one car to drive to the venue.
No
Portland International Airport (PDX). The venue is 1.5 hour from the airport.