The GPS module runs from +3.3V power and uses 3V logic. the GPS is powered directly from the 3V and GND pins on the bottom left of the Feather. Each Feather has a regulator to provide clean 3V power from USB or battery power.
The GPS module, like pretty much all GPS's, communicates over UART serial. It sends ASCII NMEA setences from the GPS TX pin to the microcontroller RX pin and can be controlled to change its data output from the GPS RX pin. Logic level is 3.3V for both.
The baud rate by default is 9600 baud, but you can configure the module to use different baud rate if desired
The GPS is wired directly to the Serial pins at the bottom right of the Feather. Note that on the ESP8266 Feather this is used for bootloading so the GPS module is not recommended for use with the ESP8266! The other Feathers use USB for bootloading, so the hardware Serial port is available.
If you need to connect to a different set of pins, you can cut the RX and TX jumpers on the bottom of the board
And then wire your desired pins to the RX and TX breakouts right next to the FIX LED
The GPS module has some more pins you can use:
GPS Reset - you can use this to manually reset the GPS module if you set the baud rate to something inscrutable or you just want to 'kick it'. Reset by pulling low. Note that pulling reset low does not put the GPS into a low power state, you'll want to disable it instead (see EN). There's a jumper on the back if you want to connect the GPS reset to the microcontroller reset line
FIX is an output pin - it is the same pin as the one that drives the red FIX LED. When there is no fix, the FIX pin is going to pulse up and down once every second. When there is a fix, the pin is low (0V) for most of the time, once every 15 seconds it will pulse high for 200 milliseconds
PPS is a "pulse per second" output. Most of the time it is at logic low (ground) and then it pulses high (3.3V) once a second, for 50-100ms, so it should be easy for a microcontroller to sync up to it
EN is a true 'power disable' control line you can use to completely cut power to the GPS module. This is good if you need to run at ultra-low-power modes. By default this is pulled low (enabled). So pull high to disable the GPS.
The GPS does not require but does benefit by having a coin cell backup battery. You can install any "CR1220" sized battery into the holder. The GPS will automatically detect the battery and use it as a backup for the ephemeris memory
There is a small button that will connect the microcontroller RESET pin to ground for resetting it. Handy to restart the Feather. Note that this is not connected to GPS reset unless you short the jumper on the back!
You have two options for an antenna. The GPS module has an antenna on it already, that's the square tan ceramic thing on the left side. If you plug an active GPS antenna into the uFL connector on the very right, the module will automatically switch over to the external antenna.