In my opinion, the biggest filter is just getting accepted into medical school. Once you are in, there is a high probability that you can finish and become some type of physician, although maybe not the specialty you want. I know some people who reapplied four consecutive years before they were accepted. One attending physician in an extremely competitive surgical subspecialty recently told me he took the MCAT three times.
Other filters include the licensing exams (USMLE Step 1, 2, 3) and the residency match. The number of residency spots for certain specialties are not growing nearly as fast as new medical schools. If you want to do a primary care specialty, this isn't a concern. However if you want a surgical specialty, radiology, dermatology, etc, you need to truly be an exceptional applicant.
During those initial two years, I took all the prerequisite classes, volunteered, shadowed, wrote application essays, took the MCAT, and flew around the country for interviews. You should strongly consider working as a medical scribe during this time. One interviewer at my preferred school told me, "if you aren't accepted, you need to go work as a scribe and reapply". I wasn't accepted there.
Your CS research and working experience will help. I personally do not think you need more research just to get accepted. But certainly if you want a competitive specialty, while in medical school, you will need to be listed on multiple publications in that field.
Good luck!