Integration with Homey

[Gand41f]

I am using Homey (https://homey.app/de-de/) as my primary controller for my smart home and was looking a solution to detect who is in which room: Room-assistant seems to be perfectly suited for this. However some points are not clear for me from the documentation:

1.) How is the API working? As far as I understand it uses MQTT? Or are there other possibilities?

2.) Did I understand it correctly that it detect also which BLE/BLC device is in which room and not only that a room is occupied?

3.) Are the 100ms update rate realistic for BLE? Or does this consume too much energy for a beacon/or smartwatch me and my girlfriend would be wearing?

Thanks for your help in advance.