IANAPhysist either, but I am pretty good at math.
Yes, FTL communication leads to causality violation. The "tachyon pistols" is a thought experiment that explains it:
http://sheol.org/throopw/tachyon-pistols.html
You can argue this, I guess, but it falls out of special relativity. If these experiments already done actually do propagate a signal faster than light then engineering a paradox would not be that hard, and that would be huge news.
"By carefully adjusting the frequency of the voltage and the phase displacement the researchers say they can make the wave travel at greater than the speed of light. However no physical quantity of charge travels faster than light speed."
The experiment in the article is fundamentally the same as sweeping a laser across the moon. As I read it, they're basically shoving the EM field enough that one part wiggles, then another part wiggles, and if you calculate the "speed" as if the wiggles were a wave moving from one place to another then you get a number faster than light. However, the wiggles aren't actually causing one another and don't transmit information in the direction of propagation.
One of the funny things about special relativity is that subjective time slows down the faster something moves. An atomic clock in orbit ticks slower than one on the ground. When you hit the speed of light (you can't, if you've got mass, but say you're a photon) then time stops entirely. Photons do not experience time.
Actually, all photons move at the speed of light. The apparent speed of light can slow down, by putting a bunch of atoms in the photon's way. The photon is absorbed and another is emitted, and that takes time. It's possible to take that emission and slow it down almost arbitrarily, "freezing" light.