Advanced Technology & Research interview questions

I was initially contacted from HR about an hour after applying online through a job board. We talked briefly about my resume, then she asked about any limitation that I may have in obtaining a secret clearance. Understandable, as secret clearances are pretty expensive to sponsor. After the screening, I was called by an ATR engineer about a week later. We talked in depth about the job role, my resume, and I felt he was just feeling out how I could explain my research (I'm a PhD). About a week later, they called to set up an on-site interview . They flew me up and paid for a rental car. I stayed with a friend. ATR does some military contract work, and this position was at a military site. I interviewed with the civilian engineers, as well as the ATR engineer whom I'd spoken on the phone with. Mostly talked about my resume, the role that would be required of me. Then a tour of the lab. I left with a good feeling about the position, the people, and the area. They contacted me about 3 1/2 weeks later with an offer. I'll note too that I was a few months from graduating, so the timing of obtaining a secret clearance (up to 3 months) worked in both of our timelines.