Spirit System

I'm still trying to get a grip on what some of telemetry sensors actually tell me.

On a Spirit GT / Castle Edge ESC / FrSky ACCST 2 RX I get the following:

RX ??
RxBatt Receiver / BEC Voltage
Fuel Vibrations
ADC2 ??
RBOX V1 Main Battery Voltage
RBOX A1 Main Battery Amperage??
VFR VFR
RBOX C1 ??
RBOX C2 ??
TEMP 1 ESC Temperature
GPS Alt Altitude (Seems t work without GeoLink. Barometer in the Spirit GT?)
RPM RPM

I'm interested in getting more info on the sensors with ??. Also, The RBOX A1 is a Amp erage display. But what is it supposed to show, the total battery capacity, the rema
ining capacity?

Also, what the difference between RSSI and VFR

I'm running this on a FrSky X20S with Ethos, and assuming this is similar to the OpenTX integration Telemetry, then I think some of the questions are answered

RX = ??
RxBatt = Receiver / BEC Voltage
Fuel = Vibrations
ADC2 = ??
RBOX V1 = Main Battery Voltage
RBOX A1 = Main Battery Amperage (Is this a value that's calculated or manually entered? IS it the battery rated capacity?)
VFR = VFR
RBOX C1 = Battery Consumed Capacity (in mAh)
RBOX C2 = BEC Voltage x10?? IS this the same as RxBatt?
TEMP 1 = ESC Temperature
GPS Alt = Altitude (Seems to work without GeoLink. Barometer in the Spirit GT?)
RPM = RPM