Questions for pursuing a PhD track in epidemiology

[tryinnaaskquestions]

Hi all, I currently work as a full time clinical dietitian, but have lately been thinking about going back to grad school to pursue a phD. I completed my MS with my dietetic internship and thoroughly enjoyed the research process. I'm posting this in this subreddit due to a growing interest of mine to pursue a career in epidemiology after getting exposure to public health through previous courses, volunteer experience and work in the hospital.

With that said, I do have some questions I couldn't really find good answers to online.

1. What are some general qualifications for admissions? I have a background in math, and have taken college level calculus, stats and physics classes, but despite excelling in them it has been a while since those classes (7 years the most), so I am quite rusty right now. As far as research goes, it is spread across several different fields. I had 2 summers worth of research with brain cancer in a clinical research lab. In 2015 after switching more towards nutrition, I also volunteered and got a job researching macronutrients and metabolism in a metabolic kitchen.

2. Upon completion of the PhD program, what specific jobs outside of academia are available?

3. Are there jobs in research at the government level? It would be good knowing there is backup in case a career in academia doesn't pan out.

4. And how good is the job market for these fields outside of academia?

5. I briefly ran across several online job websites such as indeed, glassdoor mostly involving designing and implementing research at the population level. These jobs require a PhD, but also prefers 5-8 years of experience. Where would a new grad obtain this experience?

Anyways, quite long of a post, so thanks to all that have taken the time to read through it!