The Pilot app allows you to
change the Home Point you recorded at the time of launch to either the current location of the RC, or the current location of the aircraft. You must have an RC or tablet with GPS capability to do the former. The P3 RC does not have GPS, but the Inspire 1 RC does. So, using the P3 RC, to change the original HP at launch to the current RC location, you need either a cellular tablet, or one with built in GPS, or a BT connected external GPS, like a Bad Elf Pro.
Compass calibration does not set your home point, but the aircraft will, as it warms up and finds enough satellites. The original HP is set to the aircraft location, using the aircraft GPS.
Recalibrating your compass should only be necessary if your last compass calibration was faulty, or you are more than 50+ miles from where you last successfully calibrated it. Recalibrating before every flight only introduces possible new bad compass readings that overwrite your good compass reading. Once you get a good one, leave it alone, unless you have travelled a long ways away.