Hi,

It depends on the role you are applying to:

1. Experienced hire for a generalist position
2. Research expert
3. Expert hire in a particular practice (e.g. implementation coach in Digital)

1. Experienced hire for a generalist position - this is basically the same as the generalist. Your expertise will help you with staffing on particular projects

2. The research expert is a supporting (non-consulting) role. Here are the implications:

• You are specialized in a particular industry sector
• You may or may not be assigned to a project. In most of the cases, you will have limited client-facing activities.
• Lower salary
• No international staffing, though lots of remote work with other offices

3. Expert hire in a particular practice - it's a more client-facing role:

• You are specialized in a particular function
• You will be assigned to a project. You'll have quite a lot of client activities
• Salary might be comparable to consultants
• International staffing opportunities

Answering your second question, you will have 3-4 case interviews with FIT and some industry-specific questions. You should know:

• Latest trends in your field
• Key analytics instruments and examples of how you applied these tool in your past
• Applicability to different industries

I think the best way to prepare is to find the relevant technical articles and knowledge nuggets on McKinsey official site - they have plenty of them.

You may also be hired for some data-science positions. In this case make sure that you know how to work with excel and databases (sql, Python, etc.)

Good luck!