Yes, static is most likely to cause ignition of vapour and can come from many sources.
As you say static from wrong clothing, running water,someone with a sack barrow walking past or also as you say the actual tank being filled.
But mobiles still present a risk albeit a smaller one than static...
No I'm sorry I don't know the answer to that.
I think it's minimal and unlikely to cause ignition.
But if the LEL of the Gasoline vapour is reached then it could be a possibility albeit a small one.
The electromagnetic signal from a mobile being a potential source of ignition has been questioned...
Yes they have,due to electromagnetic radiation
And they can cause explosions due to them not being intrinsically safe.
The biggest cause of gasoline ignition is usually static from peoples clothes.
It's common in the States where people have bigger tanks so set the pump running and walk...
It looks like you have triggered the wrong fuel/anti theft device.
Look in the boot where your spare tyre would be and there is sometimes a tool which you can use to de activate it.
Usually a red or yellow plastic thing with an arrow on the end.
Try the glove box too,some cars hide them in there.