The Wi-Fi Remote can control up to 50 cameras.  If multiple cameras are paired to a remote, the remote controls all cameras at the same time.  This means that individual cameras cannot be controlled separately by the remote.

The remote can control any combination of camera models as long as the remote version is not lower than 2.1.7.  If it is on a version older than 2.1.7, you will need to update the remote software.