Partly yes, although Abrasion Index is specific to the mineral's effect on crushing and grinding equipment; more specifically to the consumable metal parts involved (cones, liners, balls/rods, etc.)....
No. Resistance and density are unrelated properties; for example, salt water is denser than oil, but has a much lower resistance.
abrasion resistance is the resistance in abrasion
Their moral is much higher
A: practically any series resistance will do that