How important is the historical background?
How do you know that you have actually investigated what you intended to investigate? You should aim to describe weaknesses as well as strengths. Academic writing often means having a discussion with yourself or some imagined opponent.
But you also need to say why and how it is possible to use more than one approach. Placing your thesis in perspective In the final section you should place your work in a wider, academic perspective and determine any unresolved questions.
Something that is bespoke to what they are about to encounter. This is because a narrower scope lets you clarify the problem and study it at greater depth, whereas very broad research questions only allow a superficial treatment.
How much time and space should you devote to the theory chapter?
Narrowing the scope of your thesis can be time-consuming. Most importantly, a research question is something that can be answered. Paradoxically, the more you limit the scope, the more interesting it becomes.
In other words, you investigate a phenomenon from several different perspectives.