You can't increase the range, but you can increase the number of available channels in one room. The range is already very large, e.g. you can cover a whole stadium with only one AP4.
It can be done via the analog interface, via Dante, or via a mix of both.
You'll need to pair it with a code the very first time. Afterwards, you'll be able to pair it again quickly like any other hands-free device.
As many as you need, there is no limitation.
Three persons can speak simultaneously in one group, and you can choose the configuration, e.g. "1 guide + 2 visitors" or "2 guides + 1 visitor". You can also limit the number of participants at the same time.
4 hours of charging are necessary for 18 hours of autonomy.
Up to 300 meters without obstruction.