I asked our head of English this one - he said that they're really unlikely to have a question which asks you to focus on language/techniques, but it's good to know so you can weave them into your essay. For example if you're doing a productions question and you're talking about Act 1 Scene 1 in a feminist viewpoint, you can talk about production techniques you use to establish Lear as the figurehead of patriarchal power. Then you can say that Lear's authority is further emphasised by his use of language - use of royal plurals, imperatives, etc.