Joe says:

If the UK exits the EU, how easy or how difficult will it be for UK musicians to perform in Europe?

Impossible to know. What sort of Visa requirements might be imposed by either size is an utter unknown. Those on the 'Leave' side, may claim that everything will be fine, but they're only guessing...

McGrath says:

I've never understood why they prefer a X to a tick. In most situations a X indicates you are rejecting something, whereas a tick means you support it.

I assume that it goes back to the time when an 'X' was used by the illiterate to show assent to a written document. Whether that predates it's use for an answer being wrong, I know not.