Hey Dan-
If you've been to TBF, you will do very well at folks fest. It is a lot more mellow than telluride and certainly Rocky Grass. I do believe you are right on the north camping area being quieter, but can't say for sure as my whole crew/family camp in Meadow Park.
As for needing a vehicle pass, to me it sounds like you will not. You can drive your car in for load in/out. Not having a vehicle pass will give you the option of either north or south spots.
I have been to all 3 PB festivals many times and I love folks because the music is of course great and the vibe is quite smooth.
As for exploring the area beforehand, do it. My Dad lives in Lyons and that area is amazing.
Hope that helps. FESTIVAL!!!!
Nate
Listening to:
New Martin Sexton