As far as #2 goes, I dont think it will. The BOV only works when you close the throttle plate. It lets excess air vent out and prevent damage to the turbo. With an automatic you never let your foot off the gas for the most part. It might blow off a little when it shifts thats about it i think. The only auto turbo cars I ever see are full race cars and they dont use BOVs.

#3 there is a lot of variables