1.I think GPS spoofing is much more difficult than jamming.You need to be able to the track the victim aircraft so that you can radiate it with a false position that convincingly deviates from the true track. That needs an independant track and a GPS simulator ---band of skilled engineers required and then only kill one target. Jamming you can do with a load of thugs.
Unfortunately, you don't need to track the victim aircraft.
GPS satellites simply broadcast their own positions and the time of day. A GPS receiver receives these broadcasts, which allows it to determine the position of all available GPS satellites in space. It then measures its own distance from each satellite, by comparing the time of day of each broadcast message with the time of day at which it was received by the GPS unit. The unit then determines its position through triangulation. This is a vast simplification, of course, but that's the basic idea.
The GPS satellite signal is extremely weak. In fact, it is actually lost in background noise. GPS units locate satellites by using known PRNs and shifting replicated broadcast signals in time until there is a slight jump in signal strength. It's delicate but, amazingly, it works well. However, the weak signal means that it's very easy to overpower the real-world signals with local, spoofed signals.
So spoofing simply requires overpowering the real signals and substituting fake signals that are correlated in such a way that they place the fake "satellites" in different positions. This will give any listening GPS unit an incorrect position for itself. Thus, spoofing moves all GPS units in space. You don't have to target an individual airplane … but then again, you don't have the option of targeting an individual airplane either—all spoofing affects all units in range, and the range depends mainly on line-of-sight and transmitter power. And remember that the transmitter need not be stationary on the ground.
RAIM cannot detect this type of spoofing. All the signals look good, and the GPS unit has no way of knowing that they've all been spoofed in a coordinated way. Everything fits, and yet the position given by the "satellites" is completely wrong.
The military gets around this by encrypting its precision code. Military GPS units have encryption keys and units that allow them to decrypt the encrypted signal. Civilian units can't use the signal. Since spoofers typically will not have the encryption keys, they cannot spoof the encrypted signal (that's why the military calls it "anti-spoofing," because that was the original goal). Unfortunately, encryption is not an option for civilian use, because every civilian user would have to have the keys, which would mean that they couldn't possibly be kept secret from potential spoofers.
Jamming is way easier. You just blast out noise on the GPS frequencies (easy to do because all satellites use the same frequencies). RAIM will detect this—but even if RAIM detects it, you're still deprived of GPS. Which means that if GPS is your sole or primary means of navigation (LORAN shut off, VORs decommissioned, ILS removed), you have a very big problem.
My worry is that, while paranoid government authorities pour all their time and energy into having people remove their shoes in airports, the bad guys are preparing GPS spoofing equipment. One day, they turn it on, and a hundred aircraft crash at once. I think we are protected to some extent in that it's much more difficult to spoof GPS than it is to put a bomb in a suitcase, but I don't think we should depend on that.
As for WAAS and LAAS, neither of which is part of GPS: WAAS can be spoofed in a way similar to that of GPS, but LAAS is much more difficult to spoof or jam, because it's local, like an ILS. You might be able to mess up one airport (and that would be pretty bad, and ironically LAAS would make it easier), but everyplace else would be unaffected unless you had multiple local spoofing transmitters.