Technically true, and practically questionable because of the psychological way the jury system operates? Which is to say, in the face of that absolutely correct power, the system has developed unfortunately clever ways to make this not seem like the case, see e.g. the undeniable truth, and yet incredibly powerful taboo of even mentioning, "jury nullification."
Eh nope. At least not in common law jurisdictions. I recently sat on a jury (murder trial) in a common law jurisdiction (Republic of Ireland) and the sitting Judge is the judge of Law, and the Jury is the judge of Fact. Apart from that the jury does what it's bloody well told.
Continuing with your metaphor, the symphony conductor "only conducts" -- he or she doesn't play the instruments.
The judge sustains or overrules objections. They decide what topics may be presented at all via the Motions in Limine [1] which are incredibly important. And much more.
Kinda. The jury is the "fact finder" so only they can decide someone is or isn't guilty. However, a judge has the power to dismiss a case before sending it to a jury. They can say, essentially, this case is easy to decide so we don't need a jury. I'll just decide it now.
Except the judge’s rulings determine what evidence the jury is shown. And the judge can overrule the jury with a JNOV - a judgment notwithstanding the verdict.