All great questions to ask on your interview day. Answers from a current Pathways student:
HST/Pathways are two separate tracks with two very different cirriculum. We have orientation and one other month-long course together, but otherwise you will be seeing your Pathways colleagues much more than your HST colleagues. That being said, I have Pathways MD/PhD friends who go to the MD/PhD retreats/events, and have friends in both programs.
I would hesitate to generalized pathways vs HST students. There are some Pathways students who love research, and there are some HST students who love clinic. That being said, I think the Pathways cirriculum is much more focused on clinical medicine, whereas HST gives you a deeper dive into the basic science.
As someone not in HST, I cannot comment on how math intensive it is or is not. You cannot just switch between HST and Pathways. They are two different programs, and if you only applied to Pathways that is the only one you can receive an offer of admission from. I'm not sure what you mean by "are pathways courses not that orientated towards research", but if you clarify I can answer that question as well.
Feel free to PM with any additional questions