Just did a ride up Nacimiento-Fergusson about 3 weeks ago. Ride report with a few photoshere
. You do not need papers to go through N-F road... you do need papers to go onto the actual base itself. We stayed at The Hacienda which is a converted mission on base... it was very nice.
Yes, watch for dirt/gravel in the turns and definitely stop and take in the views! The suggestion for 229 is a must if you haven't ever ridden it... it is also called Rossi's Driveway and for good reason.
Lots of great roads through Paso Robles as well... Vineyard, Adelaida, Peachy Canyon, and Chimney Rock to name a few. Also check out Old Creek and Santa Rosa Creek Rd. near Cambria. Lots to choose from!