Not sure I could sort out the description.
Display requires 5V whcih can come from usb or main power over 5V regulator on Arduino. Later does not seem to work.
The error messages come from moves to illegal positions. Divide x/y by steps per mm to get real coordinates. Maybe you just defined print radius too small.
Part of your description sound like your board resets when starting print, is that correct? See log for the message "start" and restart reason. Might be related to the bed so maybe try a print without bed enables like before the changes.
