Not necessarily. Sometimes I turn off the adblocker for days and still have the requests when turning it back.
Adguard Home or Pi Hole, in a device that, indeed, can be a Raspberry Pi.
I have an adblocker for my home connection. By far, Hue subdomains are the most common blocked ones.
Philips Hue sends data to servers every few minutes.
Not necessarily. Sometimes I turn off the adblocker for days and still have the requests when turning it back.