Is it a Constitutional requirement in the U.S. that people be presumed innocent until proven guilty?

if charged with crimes?

It is a principle of law that relates to the prosecution's burden of proof. It only applies in criminal matters. The Latin phrase is, "ei incumbit probatio qui dicit, non qui negat" which translates to: "the burden of proof rests on who asserts, not on who denies."

It doesn't say that anywhere in the constitution, but the 5th, and 6th ammendments encompass legal rights of defendants as a matter of due process.

It is not specifically mentioned in the constitution, but the due process clause ("No person shall be...deprived of life, liberty, or property, without due process of law...") of the 5th amendment means that basic standards of fairness have to applied to all civil and criminal court proceedings. Just what those standards are is not explicitly written out in most cases, but comes from common law, the law of precedent, which has its roots in Britain. The presumption of innocence in fact was ingrained in Americans well before the constitution was ever written.

That phrase does not appear in the constitution. Instead, what appears is the due process clause. The Supreme Court has construed that to mean that the prosecutor bears the burden of proof at trial and must prove the case beyond a reasonable doubt. The phrase has no meaning beyond that burden of proof at trial.

No, it is interpolated from the rule that the prosecution must prove guilt

Yes. In court.