True but if you see in NA only two or three players flex for the team. Tenz on SEN, Asuna on 100T, Victor from NV all play the primary duelist regardless of map pick. By making them comfortable in their roles teams benefit from the players' confidence to perform their roles well.
Correct. They like using Brimstone/Viper together and also use Skye a lot. The one thing I see that is different from most other regions is the heavy use of Cypher.
I think the main reason for that is team play styles. NA have an aggressive play style that suits them better than EU who rely more on trades than individual gunfights.