Is a 4.0 out of 5.0 GPA for high school good enough for med school?

What you get in high school has absolutely zero influence on medical school admissions in the U.S. a 4/5 is roughly a 3.2 unweighted GPA on a 0-4 scale. A college GPA of 3.2 would not be good enough to get into medical school.

Your high school grades don't count for medical school, but you should be able to get into a good college if you've been taking challenging courses and your test scores are good.

No.

Medical school only cares about your college grades. They won't even ask for your high school grades.

Just so you know, most colleges do not use weighted grades. They use raw grades on a 4.00 scale.

Depends on the med school, and on other factors in one's application like the introductory letter and how well-written it is, the interview, and extra-curricular activities and/or accomplishments.