For Siri, scenes, and automation settings, you can visit the following link: https://support.apple.com/en-us/HT208280
2. Remote Control: To control your HomeKit devices remotely when you're away from home, you'll need to set up a HomePod, Apple TV, or iPad as a home hub. This allows you to access and control your devices using the Home app on your Apple device from anywhere with an internet connection.
3. Device Sharing: While you can't share individual devices, you can invite family members to your HomeKit setup through the Home app. This allows them to access and control all the devices and scenes within the home.