The person called me at an odd hour, somewhere around 9-10pm. And started talking about how the job would require me to be working 12+ hrs a day plus night shift on top of that too on atleast 2 days of the week

Easy and short. Friendly interviewer, good experience. Nothing too challenging. So there's no need to prepare for it. The person asked sbout prior experience and gave a little explanation about the job and whatever it entails. All the best, i think everyone should get it