You could do this without an Arduino. An op-amp as a comparator could detect the change in the photoresistor, and then you could control an analog switch or a driver & relay. And for on-off you don't really need a digital pot. (And, you would need the microcontroller if you're going to use the pot.)
But, if you want to us an Arduino your parts should work.
I am trying to build my own mini speaker project with a function (when a hand covers over the speaker -> it mutes the sound.)
What happens at night?
...not too sure if Bluetooth is complicated)
It would have to be a stand-alone Bluetooth audio receiver. The Arduino isn't fast enough for Bluetooth audio.