Interview process at Microsoft is very well-organized. Typically, you go through a "loop" consisting of meeting 4 - 6 people in a day, and an "as appropriate" at the end --- that person will meet with you if you have enough "hire" recommendations from the people you've met earlier in the day. If you don't meet with a more senior person at the end of the loop, you probably didn't get enough "hires" earlier in the day.
Microsoft is unbelievably disrespectful in the timeliness of its communications. You can HR, the people you've met, and just about anyone else to "go dark" on you for what can seem like an eternity (especially when you are looking for a job). It's just plain mysterious. People won't answer emails, or calls --- don't take it personally. There just isn't a culture of respecting people who aren't "in the fold" (unless you are a customer paying for something).
Interview questions can vary greatly. If you are interviewing for a position in a "hot" part of the company (Xbox, for example), you can expect to meet some younger type people who are very full of themselves, and think you should feel lucky talking to them. Just deal with it. You will likely get ridiculous questions like "what is your true passion?" or "how do you want to use technology to change the world?" ... things along those lines.