If you missed yesterday's You Are the Ref post, here it is. Answers below!

Keith Hackett’s verdict
1) Yes, but not because the shirt is the wrong way round. He went off under Law 4 (concerning players’ equipment), so cannot return until the ball is out of play and you have checked the condition of the new shirt. You need to deal with this by stopping the game, showing him a yellow card for coming back on without your permission, and then having him change again so his shirt number is visible. Restart with an indirect free-kick to the opposition, taken from the point where the ball was when you stopped the game. John Feldman wins the shirt.
2) It’s all about safety here. You have to determine whether these leather ridges could represent more of a danger to this player and his opponents than conventional studs. Looking at them, I’d allow the player to go ahead and wear them – though it would have been better to have been made aware of them before the game began. Thanks to Caleb Gray.
3) It’s something else. Award a normal throw to the opposition. The ball entered the field of play in a legal way, and the last player who touched it was the throw-taker. Imagine a long-throw specialist who somehow managed to throw the ball out over the opposite touchline – it’s the same here. There’s no offence to punish.