Pilots should only deselect a GPS satellite via FMC in the very rare event of a malfunctioning satellite that ground stations failed to shut down, and only when a NOTAM instructs them to do so.
Despite ADS-B data showing tail numbers to ATC, pilots must continue to use conventional methods for identification and contact; merely announcing a tail number is insufficient for ATC to locate an aircraft in busy airspace.
Most standard GPS approaches (titled "RNAV (GPS)") are indeed RNP APCH procedures, and general aviation pilots with certificated GPS systems are authorized to fly them, with only RNP AR approaches typically requiring special authorization.
Autoland features spark debate: some pilots feel they detract from the joy of flying, while others see them as crucial safety systems that can prevent accidents (e.g., pilot incapacitation, pressurization issues, disorientation) and help attract more people to general aviation.