BASE STATION RANGE OF OPERATION

I have the same setup, but without the finished basement.  I do have sensors on all of the windows, a motion sensor, two camera, and a siren in the basement.  I have a camera and a siren on the second floor.  All of my windows and doors on the first floor have entry sensors.  I also have two cameras, three locks, four motion sensors, and a glass break sensor on the first floor.  I have the base in the center of the first floor, in a cabinet.  Occasionally, I lose contact with my garage side door lock, but it's only happened a few times.  Other than that, the location has been flawless for me.  I've been told that having the base on the second floor works well too.  I wish I knew how the antennas were set up in it.

No, the base stations don't talk to each other.  You could have multiple bases, but each would be controlled separately, and you would need a monitoring plan for each one.

But you can have as many keypads as you want