I think the altitude readout is mathematically calculated from the GPS satellites. I believe the FC does have a barometer, but with no way to set the local barometric pressure, the accuracy of all altitude readouts is questionable. Regarding the GPS - yes, I ordered the drone with GPS installed -- I am told it is an easy install as the FC and GPS modules have mated plugs and the GPS module comes with the wire to connect (so - no soldering required). #iFlightUSARepairCenter is the best customer support on the planet. Pat Byars is exceptional (and, frequently he has better than new drones available for purchase). When my wife buys me a drone for a present, she gets it from Pat.

#iFlightUSARepairCenter (and other iFlight Support Experts) recommend remaining with the installed version of BF pending iFlight and the developers resolving some compatibility/coding issues with the M10 GPS module and a few other items -- so, no need to update BF. Depending on what model of Goggles you are flying, you may need to update update the o3 air unit version via the DJI updater (consumer drones). I use the ELRS Binding Phrase and generally do not have any problem binding quads to the ELRS TX. Bardwell has a full tutorial (and I use the same method he recommends).

I use what Bardwell categorizes as a modified pinch. I have nerve damage in my hand - my thumb is "numb" so, trying to fly using only my thumbs proved to be impracticle.