Pico's Mosfet maximum Amperage when partial ly turned on?

Hi,
I'd like to use the mosfet of the pico to control power of a GPS (60 mA at 3.3V, 5V tolerant, own ldo regulator integrated).
So, I got confused somehow from the documentation...
That is, after bridging the jumper B0/Fet, I should use the example provided here we have

digitalWrite(B0,1); // Partially turn on the 'Bat' output (this produces 3.3v on the FET, meaning it has just 1.4v between Gate and Drain)
digitalRead(B0); // turn off the output (also check if USB powered)

a-Does that mean that I will get a 3.3V on VBAT?
b-What would be the max amperage in this case?
c-Would the mosfet get hot?
d-On this Pinout, which pin should I use to connect a load that will be powered through B0 controlled mosfet : VBAT, BAT_IN?

As a separate problem, I need to connect the GPS on a UART AND an I2C (addtionnal sensor here).
e-What would the best pins to use: B6 & B7 for UART, which ones for I2C?

Thank's a lot.