Firstly, you can add BJ/Tyler and Tyler/James to that list of FF winners turned winner-winners.
Secondly:
Is there any MAGIC involved with the Fast Forward that gives you extra powers for the rest of the entire race??
I think there are multiple benefits to a Fast Forward victory.
The first is everything associated with being able to quickly finish a leg.
If you have an injury, it gives less time for it to be aggravated (Steve/Dave in TAR 4). Similarly, if the conditions in the area are brutal, it allows you the chance to quickly find better accomodations (Meghan/Cheyne in Dubai, the unaired FF in Phuket in TAR 14).
Some of them allow you not to deal with difficult navigation (Ken/Tina, Nicolas/Donald, Nat/Kat) and/or save money (Dan/Jordan not taxiing all around Singapore).
The second is, I think, the motivational benefits. For a team that has been dragging, it can give them the needed push to continue onward (Dan/Jordan, Meghan/Cheyne, Uchenna/Joyce, BJ/Tyler). A frontrunning team can use it to further gain steam (Ken/Tina, Nick/Starr). I think it gives the confidence in one's racing ability and team (especially since the FF doesn't guarantee a first place finish) and, given how hard killer fatigue hits, I think that's probably the most important reason FF winners are fairly successful in the rest of the race.