Ok, so I’ve managed to answer some of my own questions:
Both sets of PWM pins are the same channel so you can split your signal over two controllers.
The polarity of the pins is marked on the PCB, GND is the pin furthest from the NRF24L01 module.
RX is powered via the VESC.
C-button/thumbstick is the cruise button: press to hold current speed, it doesn’t seem to allow speed adjustments while cruise is engaged, like on the Nyko Kama.
A-button is the power button, press for 5 seconds to turn transmitter on -> green LED
B-button: brake function, same as pulling back on thumbstick.
Binding seems to be automatic/pre-bound. If no connection between RX/TX -> red LED on RX blinks slow and left LED on TX is green. Upon connection -> red LED on RX blinkss fast and left LED on TX turns red.
Charging: LED next to charge port is red.
Charged: LED next to charge port turns green.
Don’t throw out the charge cable, the male mini USB plug has a non-standard length because the receptacle is mounted deep in the housing. Other mini USB-plugs won’t reach in far enough.