I first did a very short interview with a temp agency over the phone (they really just want to see that you're nice). I had to do a few online assessments for the temp agency. Then I had to do a few at the company - typing, comprehension - nothing too difficult. The actual interview was me and 4 others in the room. That would normally seem intimidating, but everyone was very nice. My future supervisor and two leads were in there, plus a regular employee taking notes (she had purple hair, that put me at ease!). They pretty much took turns asking questions. I wouldn't worry too much - if you're in a business outfit, you'll be the most dressed up. They don't bombard you with questions, it's pretty chill. I did not have to do a 2nd interview.
This company WILL verify EVERY job you have listed on your resume (just to see that you worked there). If they can't get in touch with one, they will let you know so you can help them.