Can you verify the expected behaviour of a successful flash?

Looking at the log output after reboot it seems to be establishing a configuration then saving it to flash.

Is it normal to take ~3 minutes after establishing the sensor config to save preferences to flash?

Once the saving preferences to flash message appears, is it safe to power off the device at this point?

Does the ESP32 device need to be connected to the BMS when it's adding sensors on first boot?

Apologies for the noob questions, I'm still waiting for it to click for me :)