"Reversed" wires give messages, but pins shifted vs rotated can burn the programming wiring or function based on the other thread. It you use any lead extensions, make sure that you don't have one reversed, but again, you get messages about other Jeti functions. Once corrected the timer will still program. I always use servo extensions and always carefully place them visually, out of the plane to avoid a shift.
The "donut" is a ferrite ring for RF suppression. Some crush then and remove the pieces. I cut the wire, remove the ring and solder to desired length. It seems to not make a diference in our use. Of course that is at you own risk, and I doubt the ESC manufacturer would agree by honoring a warranty.