Can i add rwb30 to an existing rbr50 mesh network

I have an existing rbr50 router + satellite which works fine, this of course is on ac3000. I have a room with a dead spot and so i purchased a rwb30 to just make a decent internet connection for that room.

my questions are the following

1. Will my connection in the entire house drop to ac2000 speed?or just the room where the rwb is plugged in?

2. Are these devices compatible even?