Typical phone interview that lasts about 30-40min so make sure you are free to do it when they call! Otherwise it may be difficult to get back with them depending on the temperment of the people in your area; first impressions make a dramatic difference.
After the phone interview, they will schedule a time for you to have a face to face interview and are seemingly very flexible with timing (at least in my area, St. Louis, MISSOURI).
Don't go in expecting an in-n-out interview, the process is drawn out a little too long for my likes (little over 4hrs for me) but once you make it to your second interview within the same day, it's a good sign but don't pat yourself on the shoulder yet, there are still 2-3 more interviews left to conquer depending on your area and position applied for.
Resume...
Have one! Even if its crappy. It helps give them a little more of an insight to what kind of person you are. It also shows them you want to be taken seriously.
In the end, if you manage to get your drug test in the same day (or later), go ahead and take a deep breath then pat yourself on the back for a job welldone, you're now a CarMax employee.