The earthquake was just coincidence.
The attack I'm going to put down to coincidence as well. The chance that they planned it specifically for Friday 13th due to superstition does exist, but I highly doubt it.
It was likely more due to just how many people were around at the time that they chose that date, with both (what I assume is) a fairly big football/soccer event and Eagles of Death Metal (who are somewhat well known, not a small local band or something) playing in one of the attacked areas. It was also a Friday night in a touristy area so there would have been that on top of it.
I'm guessing she meant plants, as in, nuclear power plants.
An attack on France to intergalactic warfare is a pretty big leap.