When working on these two chapters, I suggest you start with literature review. Literature review can help you to look deeply into the research background, can help you to clarify the research aim and research questions formulated in the proposal and can help you to delimitate you research focus and scope. Therefore, write chapter 1 after completing the literature review chapter rather than rushing into it.
This is a suggested structure for the first chapter.
Chapter 1 Introduction
A brief presentation on what you are going to present in this chapter.
1.1 Research Background
Explain the general background of where this research starts, why it is meaningful, explain brief literature with the focus of the key terms that you use to formulate your research aim and questions.
1.2 Research Aim and Questions
Clearly define a research aim. Break it into steps. Give each step a "sub aim" - research question and explain how this research questions is derived and from what aspect this research question answers the research aim.
1.3 Research Focus and Scope
The focus area of your research and the scope of your data collection
1.4 Research Methodology (complete this section after you complete chapter 3)
1.5 Structure of the Study
briefly present how many chapters, and topic of each chapter.
You can use the contents of your proposal where it can be fitted into chapter one. I suggest you use present tense and/or past tense to write chapter 1 as it presents the work and the thinking you have done.
Chapter 2 Literature Review
The literature you used in the proposal can also be used in chapter two but chapter two should be more in-depth, comprehensive and showing your critical thinking. Chapter two literature review needs at least 50 references or more (not more than 90), most of them (75%) should be journal papers. So, you need at least additional 30 references for chapter two. I am not able to give a template for this chapter as different students' research topic is different. Normally, it starts from general ideas/concepts/theories and then goes to the specific ones. It is always good to use models/frameworks. Normally, the company (companies) you use for the case study is not discussed in this chapter unless there is a reason to do so.
As to word count for each chapter, roughly, it could be
chapter one - introduction 2000-2500
chapter two - literature review 5000-5500
chapter three - research methodology 3000-3500
chapter four - case study - 5000-6000
chapter five - conclusion 1500-2000
All together, do not exceed 20,000-24,000 words and do not to be too short of less than 16,000 words, exclusive of the appendix.