I can't believe I'm saying this but:
Actually (I think) the Cobra R wing was designed, like the rest of the Cobra R, for Racing. So it actually does provide some downforce (at much higher than highway speeds). At normal highway speeds the only downforce it provides is gravity.
And yes, at least it isn't an aluminum "adjustable" multi-tiered park bench as is popular amongst the import and FWD crowd.
To answer the Mirror question, sorry but I don't know. But let me know if you find out. The more Mustang parts that will swap, the more options we T-bird owners will have.