2. (a) That's right. A plaintiff suing for defamation does not have to prove that they were identified by name in the published material. The question to ask is whether an ordinary and reasonable person would know or believe that the statement or material refers to the plaintiff. This may depend on what it is reasonable to conclude from the known facts.
In the present case, it is likely that the ordinary reasonable person would know that B was referring to other traders with whom he was in direct competition - and that would surely include A, a retailer on the same street.