7.) As mentioned GS mini is a completely different concept. It is more concerned with maintaining a constant "energy" level of the aircraft which more or less translates to a constant ground speed. This, so that in the event of a sudden wind loss/gain, the aircraft doesn't have too much speed catching up to perform.
VLS as displayed on the MCDU and calculated by the FMGS is based on the weights input and determined by us at the INIT stage. Managed Vapp speed (the default target speed as displayed on the PFD) is derived from the same. The VLS shown on the PFD speed scale is determined by the FACs which principally derive their information from the AOA vanes. The FACS provide an actual value for VLS (based on the actual weight) whilst the FMGS provides a predicted value for Vapp. The predicted value of course can only be accurate if the loading was done correctly and if the calculated masses are accurate.
We fly heavy A321s on the standard bucket and spade destinations where most women are not the 70kg they're meant to be and where after duty free the aircraft is always going to be heavier than it's supposed to be. All of this makes standard masses next to useless. On older A32xs, Airbus decided that the FMGS would be the basis for the Vapp speed. However, I believe the newer ones have a better logic that blends a bit of actuality (FAC deduced VLS) with predictions (FMGS) to give us a more accurate managed Vapp speed. We still fly a fewer older A321s and our SOP says that once fully configured, to look at the PFD VLS value, then increase the Vapp to be at least VLS + 5.