For special teams I don't think it matters right now. Special teams is a joke that needs to be fixed. It seems to be designed to produce an average reult every time.
For blitzing, I believe that it deliberately doesn't work. The Blitz SA seems to accomplish what Closing Speed does except one works chasing the QB and the other works chasing other ball carriers.
When the QB has the ball and is in the pocket/looking for receivers, he isn't classified by the sim as a "ballcarrier" I don't think, so the answer to your second question would be no. Not sure on the first, but I assume it would (not that it matters much).