"And Andy Murray DID used to talk like a Scottish nationalist - mentioning supporting opponents of England's football team, e.g."

In the first instance whether a Scot supports the English football team or not has nothing to do with politics. It is a sporting rivalry which long predates modern Scottish nationalism.

Murray didn't actually make anti-England statements. Both Murray and Tim Henman were being interviewed and as it was the run up to a World Cup the inteviewer asked Henman if he was looking forward to watching England. Henman joked that he was but that Andy wouldn't be looking forward to watching Scotland as they hadn't qualified. Murray laughed and said he would enjoy watching anyone who was playing England. It was just young guys having some friendly banter. Other journalists and people on the net turned it into a story where Murray was anti-English, some claiming that he'd even bought a Paraguay shirt, despite both Henman and the original journalist repeting that it was only banter. Murray received quite a bit of bad press and even hate male which resulted in him ever since being extremely guarded when being interviewed.

As to his comments re the referendum as far as I know he is a don't know as he has commented that he doesn't have enough information to make a decision. Though as he lives in Surrey he won't have a vote anyway! But reading between the lines it seems he is neither a committed nationalist nor unionist.