1) yes, get 70ias
It’s not only keeping 9fpa vs 10% slow
It’s also 2 faster fpa vs 50% slow (HF, decrep, impale, clay golem)
2x 15ias/15@ is great defensively anyway
2) can be good, but like it was mentioned it’s BM. Kinda easy to stack enough res to counter it, so I’d suggest to get good defensive rare jewels instead (res/fhr/life/mana/rep), to keep your claw legit for GM and it’s practically better anyway against any opponent with stacked res.
3 & 4) I know it can make sense to have a certain threshold so you can tank 1 more hit in X or Y situation. But it works in a controlled environment where you’ll know that people reach precisely this or that dmg with the GM restrictions. But in pubs? Way too hard to come up with a number that could make sense against all builds and no restrictions. So just get the maximum you can get at your budget… no magic numbers here.
5) again hard to call for pubs… some people will play random shit like their pvm fire druid with some 83 fire pen lol
Expect the unexpected, this is the jungle

But yeah, generally speaking reach max res and stack light. You could have some 11res scs for fire/psn
Kinda useless to try to stack cold