While the details are never explicitly spelled out, and the way it is revealed is a bit opaque upon first viewing, this episode plus the several which follow retroactively explain some seeming nonsensical moments:
While it was obvious Hook sailed the Jolly Roger to New York once he woke up (from Cora and Regina knocking him out) because he knew Emma and Gold had gone there, it was never made clear how he tracked them down there. But learning Tamara was Neal's girlfriend, but also involved with Greg, puts the pieces in place—she would have known who both Hook and Gold were from the descriptions/pictures Greg gave her, so she must have run into Hook and told him where Neal's apartment was, because Greg with all his spying could also have told her Emma and Gold were coming to New York and why.
After knocking Hook out, Neal and Emma took Gold to the harbor to sail the Jolly Roger back to Storybrooke...and they used Tamara's car, thus leading to their encounter where he had to confess she was his fiancee. So after this she either went with them to the docks and then drove back to the apartment, where she found Hook in the closet (which Neal helpfully hints at in this episode by saying she went to the storeroom to get her things and it was (supposedly) empty); or else found him while they were gone, went to the docks to get her car after they sailed off, then came back; and finally took him with her to Storybrooke.
As for how she could know Neal was Gold's son (thus explaining why Emma and Gold would be at his apartment), as well as know him to arrange their Meet Cute in the first place? The information she got from the storybook via August and the Dragon, and from the Home Office, since Season 3 revealed Pan knew all along who Bae was and his connection to Rumple.
At the end of the episode, it's made clear why August didn't turn back into a real man after Emma broke the curse: he wasn't being selfless, brave, or true. As he says to Neal, he was going to Storybrooke to help Emma break the curse so that he would turn human again—a selfish act. Throughout the first season, he consistently lies—dishonest acts. He may have succeeded in helping Emma break the curse, but he didn't keep to the Exact Words of his promise.
