Not sure about the rapids, etc. I've run it once (last year?), and was in a kayak, but remember Narrow Falls beeing pretty obvious from the canyon restriction. I doubt it'll be busy in there... maybe one or two other folks around.
Prolly get a licence down in Riverside, or might even stop in Walden (North Park Anglers?) on the way through and see if they sell 'em.
What does education often do? It makes a straight-cut ditch of a free, meandering brook. HENRY DAVID THOREAU, Journal