Yes, different firmwares are used in different regions.
Yes, that should be all-right.
I had some problems with arduino/rak811 as well, i think a lot of it has to do with the fact that the serial connection from/to arduino is shared with the rak811.
In my experience, it is more stable to talk to the rak811 through a virtual serial port, and when stacking, bend out the pins.
The RAK811-N firmware based on LoRaWAN 1.0.2 will be released on the official website this week
Looks like your connection to RAK Support Center was lost, please wait while we try to reconnect.