Sorry, if you’re not “free to leave,” you have been arrested. That’s what the word means.
He may or may not have had charges filed, I see different claims. But since he was handcuffed and transported across the city in a paddy wagon, he certainly was not free to leave and therefore was under arrest.
Most states require that charges be filed within 48 or 72 hours. Cops also don’t charge people. Prosecutors do that.
Not true. The police officer is the complainant. He is the one who signs and files the affidavit. The prosecutor only handles the prosecution of the case.
The cop may confer with the prosecutor prior to filing the charges (usually regarding felonies), but the cop is the one who signs the complaint. Just as you would if you had a beef with a neighbor.