First of all - McKinsey has both Interviewer and Candidate led cases. Please be prepared for both. Candidate led cases are even harder.
1) Yes. Absolutely, you should take time to make a structure
2) I will add a post re the hypothesis below. Short answer - there is no Hypothesis requirement at McKinsey
3) It's a brainstorming question and you should provide as many ideas as possible. I also recommend structuring your ideas into buckets.
4) Both quantitative and qualitative. Think as broad as possible
Now, on the hypothesis:
First of all - it's not mandatory. I would say - use the hypothesis if you are really good at solving the cases. If not - use the basic approach
There are two ways to use the hypothesis:
First - presenting a structure using the hypothesis. For example, if you are having a PE (private equity) case, you should do the following:
1) Make classic structure (market, company, competitors, feasibility of exit)
2) Make subpoints (e.g. in market: size, growth rates, profitability, segmentation, etc)
3) Present your 1st level Hypothesis:
- - "In order to understand whether we should invest in Company A, I would like to check that the Market is Attractive, the Company is Attractive, the competition is favorable and we have good opportunities for of exit"
4) Present the main 2nd level Hypothesis:
- "In the market, I would like to make sure that the market is big enough and growing;
- In the company I would like to find additional opportunities for growth;
- In competition I would like to check that the market is fragmented enough;
- Finally, I would like to check if we have potential buyers and can achieve desired exit multiples"
Another way to use hypothesis is using the hypothesis to prioritize your analysis:
1) Make a structure: "Problem in sales may be related to Sales Motivation, Sales Strategy, Sales Coverage, and Sales Process:
2) Prioritize a part of the structure based on your knowledge / common sense / available data: "Taking into account that motivation is the core problem of the sales organization, I would like to prioritize this part of the analysis"