Columbus GM Jarmo Kekäläinen stated that he wants to bring the 3 point system from Europe to NHL. As first european GM in NHL his going to be key players convincing other gms etc in gm meetings to international systems etc.
Sometimes it's better. The top end teams are better than NHL teams, but the lower level teams are much worse. The lack of chemistry can be a double edged sword in terms of entertainment value.
No, the NHL will never adopt all IIHF rules. It's ambiguous at best as to whether or not those rules produce a better product, and it's not like international rules have any sort of historical significance over the rules used in the NHL. Some rules might change (fighting) but the NHL for example would never increase the ice size and lose out on those seats for basically no monetary gain.