Lots of stuff in this subject.
You must look at the sensor requirements for the approach, ie DME/DME or GNSS or VOR/GNSS etc.
Whatever sensors are required must be serviceable prior to approach, which means more careful checking of notams.
In theory, you must deselect VOR or DME updating if your approach is based on GNSS.
You must back up LNAV posn with raw data if operating below MSA.
You may need two FMCs in certain PRNAV airspace. This allows bailout in case of FMC failure in terrain rich environments.
SOPs normal/non need to be specific to PRNAV procs.
Database of your FMC must be approved for PRNAV standards.
Proper reporting system for nav anomalies.
Training program delivered by your airline.
Benefits are purely time saving and consistency of track keeping, which will ultimately lead to 4D Nav (4th being time) introduced by around 2020!!
I think the FAA has overtaken Europe in PRNAV (suprise suprise) and they have trials in ATL, DFW and JFK.
Hope this is a reasonable summary of TGL10.