Since you have NES equipped landsoul's spreasheet tries to restrict you to soft cap arp which is at 52% (since you are higher than that you see a negative number). As stumble said stick to ArP as soon as you get to passive 75% (gems + gear + food) drop NES.
T10 2 pc is awesome and 4pc is totally worth it. For 4pc t10 avoid the hands.
For gear/enchants, you should use 44AP on hands, Berserking on both weps and Tuskar's vitality on boots. Also when you are buying gear from frost emblems buy the leather belt instead of plate.