Also note that MCTAP extends only ground contracts. Air contracts it doesn't affect. So if you're an air contract AND prior enlisted, MCTAP is free money and won't change your PEBD. I don't have the exact text on me, but what MCTAP does is extend your contract to 60 months unless it's longer than 60 months (which it is for air). So if you're ground it adds 1.5 years onto your contract, if your Air it does nothing.
FAP adds 6 months on your contract regardless of how long it is.