Yes, but just speaking to that subject would pull in tons of votes. Understandably, it cant be done with the snap of the fingers, but if McCain would just speak about that, lots of people would fix their votes right now.
Yes and no.
The Fair Tax is much to easy for opponents to spin in short order.
You've got to keep in mind that a major percentage of voters DON'T PAY TAXES, if they hear that they will start having to pay a sales tax of 20+% without a careful explanation of rebates you will lose them.
The voters who already know about the Fair Tax or could immediately see its benefit probably aren't voting for Obama to start with.