To my knowledge, an ATTiny85 requires an Arduino board (or other micro controller) to program it and then it can run standalone, this is where you would start. As for the ability of the chip, it has 5 I/O pins (2,3,5,6,7) and you have 4 actions:
- Toggle bluetooth
- Change LED color
- Play various sounds
- Toggle USB port
You could wire each action to its own pin in order to keep the fifth port open for input from your button. The PWM/Analog output that the ATTiny85 has will allow you to play multiple pitches from one port to handle all four sounds. Toggling something on such as bluetooth or the USB port uses digital output (0 or 1), which will not take more than 1 pin for each action since you send either a high or a low from a pin to engage/disengage the corresponding action.
A problem arises for changing the color of your RGB LED because you only have one output port remaining now and the RGB LED has 3 inputs. You could potentially use two ATTiny85 chips to solve this or you could also explore signal splitting techniques such as charlieplexing or multiplexing, but I think those methods cannot work with a single pin.
After that, just figure out the programming logic for sequential and timed button press triggers to engage your output pins.
A good solution to this problem would be to use the ATtiny84-20PU for a larger array of pins. Below is the pin layout for the ATtiny84:
I would recommend following this ATtiny85 program upload guide or this ATtiny84 program upload guide to learn how to get your code onto the chip.