Yes, the magnetometer is required by the G5 for full functionality with a NAV.
If the aircraft loses power, the G5 battery sustains the G5 flight display with up to 4 hours of power.
The Garmin G5 has a built-in GPS receiver and antenna (with an option for external GPS antenna connection) providing highly accurate groundspeed and ground track readouts. Plus, a dedicated rotary knob on the unit allows for easy adjustments to altitude bugs and barometric pressure settings.
Yes, the Garmin G5 delivers a solid airspeed indicator, altimeter, vertical speed indicator and turn coordinator in a single unit.
The G5 electronic flight instrument replaces for primary attitude and/or directional gyros in type-certificated fixed-wing aircraft.