How do the Red bull qualifiers work?

My first question is: How are maps ans civs determined in the qualidiers?

I signes up for the event, just for fun and am under now illusion that i will make it further than the second round of qualifiers if im lucky. While it is fun to train empire wars and i really like the game mode, there are just too many maps in the pool and tbh most of the non canon ones are not very appealing to me. In addition there isnt really much time till the qualifiers so i was wondering, if there is any way to know what map you will play on in the first two rounds of qualifiers.

Also it says that for the qualifiers matchups elo will be taken into account. I couldnt find any more information what this means. Will they group those with the highest elo difference, or those with the lowest one together? The latter would be quite unfair, but it also seems a bit weird if ACCM would have to face a 900 elo enemy. If that was the case they could directly put an elo threshold in place. Or do they have some more intricate system in place?