4. Can a person's acts (not words) be capable of carrying defamatory meaning?
The circumstances in which a hint given with one's eyes and/or hand gestures may be considered defamatory will depend on the situation at the time and the actual acts involved.
There was a case in England in 1983 in which a man went into a turf accountant (a bookmaker licensed to take bets on horse races) shop. While he was looking around, two security guards approached him and seized him without saying anything. The three men then had a conversation. After that the security guards took the man to the security office. The man later sued that shop for defamation. He succeeded and the shop had to pay compensation to him. The reason was that, at that time, many people inside the shop saw the security guards take the man away without any reason. People would have believed that the man must have done something unlawful. The judge held that, despite the fact that those people did not hear the conversation among the three men, the conduct constituted defamation of the plaintiff.
Despite the above example, you should note that suing others on the grounds of defamatory acts/conduct involves complex legal arguments. Legal advice must be sought before taking any legal action in this sort of case.