MC aka Moonchild -- I can answer some of your questions -- and put in a plug for my favorite music weekend at the same time! Yes, you can camp (although I don't think there's a shortage of cabin space). And yes, you'll be considered a daytripper. You need to register with FSGW so you're signed up for meals as well as a campsite. And I have no idea whether you also need to let NPS know. Maybe Charlie Baum, who's in charge of this event, can give you better directions.He's a known Mudcatter.
Now for the plug. The FSGW (Folklore Society of Greater Washington) Getaway has been going on for 30+ years, and is held every year on or near Columbus Day weekend in October. It's a relaxed, family weekend with lots of participatory singing, song swaps, workshops on all sorts of topics, a little dancing, concerts (sign up for 1 song/story per participant) on Saturday and Sunday nights, and usually a handful of invited "performer" guests to spice up the musical menu. Oh, and the menu includes meals catered by Debby McClatchy. Yum. I think you'll enjoy it. Introduce yourself when you get there. Kathy Westra (who's been going to Getaways since 1975)