I did a search but found conflicting info... Can I program a new key myself or does the dealer need to do it?

Programming the remote functions is easy, with the doors closed and locked. Insert a working key into the ignition and pull out 6-7 times until the hazards flash. Insert key again and turn to ACC. push the "lock" button on the NEW key, hazards should flash if recognized.

The security start immobilizer feature needs to be programmed by the dealer, some locksmiths have the scanners to program this too.

Have you actually done that and had it work?

yes on my 2011, purchased a new spare key from amazon. Again I only programmed the door lock/unlock/panic, I was not able to start the car until Nissan used their scanner to add the security feature to the vehicle's ECU.