Just a quick tip about the 5V to 3.3V level conversion: in general you can simply use a series resistor (1K ohm is good enough) to connect any 5V output to a GPIO pin on ESP8266. This is fine because most microcontrollers have internal zener diodes that protects the pin from over-voltage, and adding a 1K ohm resistance limits the current, so this is the simplest way to do level conversion with only 1 resistor.