the 40% refers to 40% of an affixes Cap. Attack Speed Cap is 60%, so 40% of 60% is 24%. Myth Stones are 30% of their values. so there is the 40% of total Caps with stat values lowered to level 20 item values. so it looks like if you had Crystal Attack Speed 44.8% on a level 20 item, it would be 11% instead, and you would only need enough Attack Speed to get it up to 24% in the Arena. (I hope I did this correctly)
depends on which Perk you have left to get. usually Hunter Perk isn’t gotten since some players just use Hunter Ring instead. all the others help with farming in one way or another.
High Voltage isn’t a Proc. Shock Element places a DMG debuff on the target(s) that lasts for 5 seconds, and can stack up to 4. with Elemental Crit, Shock can Paralyze your enemies for 3 or 4 seconds, not sure which, and while Paralyzed, you can cause +100% DMG if you have Elemental Crit DMG High Voltage.