Equality set for my information is based on % of hp and mp pool not the raw numbers. So you can have 1k hp and 100k mp if both are full, your mana and hp is equal. As for regeneration affix read again 
Change crystal affix 3000 regen for 2000 legend affix regeneartion. 2000 mp regen + 2000 hp regen = 4000 regen which is higher than 3000 crystal affix regen (max you can get 4000>3000). Doing that on ring you can now change epic crit chance to crystal crit chance. Those operation will result in a 1000 more regen, 15% more crit chance and one free affix slot on your off hand.
For the damage reduction in mana shield i can’t help becouse i dont know how it is working. Personally i don’t like equivalence becouse it gives you too much mana, and you can’t use that mana if you aren’t using manashield. So it’s only for wizard imo. With alchemy tough you won’t need manashield becouse with your big mp pool and small hp pool you will get hits to higher current mp/hp.