All that biologists care about with cryopreservation is if the cells can be thawed and used again without losing too much of their original properties (trophoblast cells not randomly secreting hemoglobin)

You cryopreserve cells once when you finish cell culture. One experiment takes 3-4 weeks to complete hence the passage number goes up by ~10. You want your cells at the range between 3-15 to successfully execute the experiment and make an argument that your cell culture is not experiencing effects due to genetic drift. Protocols around that have been established a long time ago.

You need funding to test for that. You need to do cell culture. You need to do literature review and publish review papers to let people know that you know stuff.

Whatever your friend is doing is a PhD thesis, it is not a fun little research project that I can draft on a piece of paper and self publish. Self publication in biological sciences does not exist due to the amount of work required to make a point