Hi, Jonathan. Sounds like a nice fence. Stainless steel screws are the BEST but hot dipped galvanized nails are more than adequate also. The hot dip process leaves a rough surface on the nail which prevents the nail from pulling out also. It is your choice on this but I would go with the nails for easier installation.
Waiting before finishing is necessary with pressure treated wood but the protection is in the wood from the start with the cedar. More important is the brand of stain that you use. I really don't want to start up the battle again here about which brand is best but I would check with an independent paint store that carries the top lines of paint like Sherwin-Williams or Benj. Moore. Some of the most advertized brands seem to cause the most problems.