Yes, Use the button "Set colors" for the device in the main screen, change the normal color to black to turn it off.
Yes sure you can, please take a look at my git repository. There you will find the instructions and examples.
Press the reset button 2 times, the led will start flashing in green
In most cases, this is because the email used to register the device is different than the email in your account, you can put the board in setup mode again using the button, just press the reset button, wait 2 or 3 seconds and press the reset button again. The led will blink in green. Re-register your remotsy again using the correct email.
Go to the Alexa Scenes list on the Alexa app, click on Discovery Scenes, your routines should be there, to activate the routine just say, Alexa turn on [routinename]