Very casual. Asked basic questions including "how would you describe yourself" and asked how you would deal with a stressful situation. They're mostly interested in your availability for the week.
I applied in-person. The process took 1+ week. I interviewed at MJ Cafe & Teahouse (Rowland Heights, CA) in Feb 2014
Interview
I applied in person, then got a call for an interview. Went in the store for an interview, filled out an application, then the person started asking me questions.
It was fairly simple, easy, informal.