Wow, some of those changes do seem a bit over the top. Exhaustion on lords of khorne in particular is a killer. I have a few ideas for you though squirrel, I'll pm some of the effective expansion parties I've come up with.
As to itza, they don't get anything other than 1400 gold forts, so you do sort of have them beat there. On the other hand, their forts all have a decent admin value. Quite a bit less defense though. Having magic weapons on all their saurus (but not skinks) is a pretty major advantage. But I wouldn't say that you could build an army of unequipped saurus veteran thugs and win the game. They are a bit cheap for how good they are, but even playing NI, it's hard to give up a skink priest for a mere commander. And 1-2k gold for slann? I really hope you're joking, I should show you my turn file for tourmaline and let you see how often those 4th gen slann end up with anything resembling decent paths. Getting anything above level 2 costs a fortune. That said, I can appreciate your frustration. The old chaos seemed a little overpowered to me, but comparing them to some of your competition now, I can certainly see how you could question your chances.
As to what Itza doesn't do well - forge, use death magic, and kill immortal SCs
. They also don't really make very good thugs, though perhaps they make decent anti-thugs.