I have a team of french players from NW who would like to sign-up for the WNL but they couldn't figure how to get their IDs despite trying many public servers. I told them to do the same thing you suggested to Raqqa, hope that's okay.
Yes ofc
IG-Battlegrounds will work too.
It is important to let us know the name of the server and the time the team joined. It is helpful if everyone wears a team tag. Then we can let them know their game ID's.