I dunno, depends what 'repeating' it means. It sounds like just reporting on it might be a defense, but I could see a big loophole if you couldn't be touched for effectively picking up and amplifying the original claim with some qualifying words around it.
But I think you're right that they won't want to find out in court in any case.
Yes. The law applies what is known as the ‘repetition rule’ (or ‘republication rule’). Under this rule, the liability of a person who repeats a rumour or allegation is no different to the person who first made the statement. This includes rumours or allegations that come from reputable sources like the Police or news sites. This aspect of the law has some wriggle room when it comes to establishing defences. But for at least the element of publication, anyone who repeats a defamatory statement is liable.