On my bafang I bought a hidden wire brake cut out switch that allows use of stock Shimano levers. Since you have mechanical discs it will work. Just run the cable through it, easy as can be.
https://california-ebike.com/shop/ba...-brake-sensor/
In all honesty I don't notice that the brake sensor does much. The shift sensor is pure gold however, works like a champ
https://california-ebike.com/shop/ge...r-derailleurs/
For squealing and pulsing lots of threads on how to get discs to behave. Keep them clean, even oil from your fingers can cause that. Maybe you need a better brand of pads, kool stops are highly recommended. Taking sandpaper to the rotors has helped in the past as well.