Crownstones work with any two-way switch (wisselschakelaar). If you want to install your Crownstone behind the switch instead of behind the light, you can ask your installer to add a neutral wire to the switch’s junction box.

Crownstones do not have an IP rating and are not waterproof. Usually, the junction box distributing the wires is not right above the shower, so as long as the Crownstone itself is not exposed to moisture it can be used to control bathroom lights. It could be that the switches in your bathroom will switch both the phase and the neutral wires. In that case, Crownstone cannot be used to control the lights and be switched by the wall switch.

Yes, that is possible.

Transformers are generally more expensive, since they drive the spots, have to be dimmable, have to be able to carry a certain wattage etc. Many reasons to choose spots without a transformer!

You can install the Crownstone inside of the cover of your light, or try to install the Crownstone behind the wall switch. This does require a neutral wire behind the wall switch however.

This is a question with a bit complicated answer! The change in switch state can be communicated by the Crownstone hub towards the Crownstone Event server. This will be able to update a Homey or Home Assistant hub. A Home Assistant hub with a Crownstone dongle can also receive those changes in switch state on its own. Given the incoming event those hubs can decide to switch Crownstones or other smart home devices.

Regarding installation of Crownstones, there are 3 possibilities: you can do it yourself, via an external installer, by yourself or via Crownstone as part of our subscription service. For more information about our subscription service, you can visit this page.