The core of your preparation for the job interview:
- Learn what they do.
- Learn how they do what they do.
- Figure out exactly what skills, experience and background you have that will help them do what they do faster and cheaper.
- Plan how you're going to explain #3 to them.
Everything else is implementation details.
You should have the first three figured out before you even send a resume. If you don't have what it takes to help them do it cheaper and faster, then don't waste your time applying for the job.