Electric brakes work in both direction so do not disconnect them. The stopping power is not as great because of the nature of the leading and trailing shoes when used in reverse but then again you are not backing up as fast as going forward.
As for the repair buy a complete backer plate assembly because it i cheaper than rebuilding your current one.
WBCCI 12156 AIR 3144 WACHUNG TAC NJ6
2004 Excursion 4x4
1991 34 ft. Excella +220,000 miles, new laminated flooring, new upholstery, new 3200 lbs axles