I had my first interview with Person A from HR, who set me up with an interview with the hiring manager. After talking with him I had one more technical interview. Person A then called to tell me that I was no longer under consideration. Two weeks later, I get an email out of the blue telling me to make flight reservations to go to Minneapolis. Turns out Person A thought I was someone else when she called me. I made reservations, only to get a call the next day telling me I was no longer under consideration. Literally an hour later I find out that they want to have me interview for another hiring manager at the same location, for a higher-level position. I went out to Minneapolis the next week and was told I was unqualified after the interview (keep in mind, I had originally applied for a lower-level position). The whole process was a disorganized mess.

usually easier to have current employer recommend you. Campus recruitment is another major one. Usually phone interview for quantitative questions and behavior questions, and then onsite. Depends on the group. Some group have more rounds.