There are few enough IPv4 addresses that just about any hash forms an injective mapping which can be completely reversed: the best you can do is use something like HMAC and "pepper" it, but that only works if the clients can't verify or generate them.
No, but you can definitely identify collusion. It's really very simple. When you see the guy with JJ fold preflop and the two remaining players have, say, AA and AQ, it suggests that JJ and AA have colluded to keep AQ in the pot. So you build a pipeline to process and detect this sort of thing. It doesn't have to be realtime. Same day would suffice. Besides, you will need hundreds, maybe thousands of hands to classify it reliably.
And you can be certain that none of that is happening in this example and I'd never play there -- unless I wanted to collude with friends.