Did you disclose all of your prior college enrollment on your application? If you did not disclose your enrollment, you probably lied. Bad idea.
Yes, your visa can be denied for a myriad of reasons. The main reasons would be suspected intent to immigrate, prior US visa violations, or insufficient funding.
Generally speaking, yes. That said, no institution would be required to accept you as a transfer applicant if there’s a problem with your application (e.g. if you were kicked out of community college for lying on your application, or you don’t have sufficient funding to pay for the Bachelor’s degree, or your community college GPA is too low, etc).
Possible? Yes. Likely, no. Most highly selective private universities only accept a handful of transfer students each year.
If you do get accepted, you will be playing catch up to your classmates who had waaaay more opportunities than you did in the first two years of college, and probably going years back further. It’s miserable. The two community college transfer students I knew at Stanford - both academic superstars in community college - were struggling just to graduate. They both broke down and ended up involuntarily committed to a psych ward part-way through. You are more likely to be successful if you transfer to a slightly less competitive university with a smaller gap between the incoming transfer students and the rest of the student body. Or to a public university with a larger population of community college transfer students.
As an aside, “health science” is not a good major for your associate’s degree if you want to transfer to a highly selective university. Choose an academic major instead.
The most popular pre-med major in the US is biology, followed by chemistry. Any major will do, as long as you complete all required pre-med coursework. (The most common requirements are 2-3 years of chemistry, 1-2 years of biology, 1 year of physics, math up through calculus and statistics, 2 courses in English composition, and possibly a psychology course. You’ll want to take the most rigorous versions of the science courses, not the simplified versions for nursing students or other ‘health science’ majors. The course catalog at your community college should point out which version of chemistry, biology and physics is recommended for pre-med students.)
CAUTION: most US medical schools will only consider applications from international students if you can prove that you have funding for the full medical degree. That may mean depositing the full cost of attendance for all 4 years into an escrow account before you are allowed to set foot on campus - right now that’s about $300,000.
If your goal is to become a physician in the US, there’s a much cheaper route: complete medical school in your home country, get your foreign medical degree certified as equivalent to the US medical degree by the [Educational Commission for Foreign Medical Graduates](https://www.ecfmg.org/certification/requirements-for-certification.html), take the [US Medical Licensing Exam](http://www.usmle.org), and then participate in the [Match[/url] to be placed into a US residency.
The ECFMG can sponsor your J-1 visa for the duration of your residency program. After residency, foreign physicians can self-petition for a green card via [url=https://www.uscis.gov/greencard/physician-NIW]National Interest Waiver](Intro to The Match | NRMP) if they make a commitment to work in a medically underserved setting for 5 years.
Good luck!