No the bracket doesn't need a ground. The wiring is option wiring that isn't in the car if this option wasn't purchased. Believe it is a purple wire to the rear blower. When I installed one in mine, I just got a chunk of red strained #14 from Home Depot.
I thought I would add this. If you are interested in a factory like installation. M&H has the complete harness for $35.00. Should be from the fuse block to the switch to the defogger unit (ask to verify).
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