Midi Extender questions

Hi there, Have built up the midi extender for this but wanted to ask a few questions: 1. What is the wiring for the midi cables to the pins on the PCB? Nothing was marked. 2. Do I need to cut the trace on the teensy if I'm going to use the USB cables as a host and also T4.1 while the unit is turned on in the modular rack? I'm guessing so. 3. And to cut the trace, you just use a sharp knife to trim away that tiny line on the teensy underneath? Just really getting into testing it now, but its been an adventure. Screen clearance is a bit problematic finding a way to connect it to the PCB with the jacks 10mm clearance gap. Trying to find pins or a housing to work took a bit of cutting.