For a moment, Castiel had been nervous to the point of being fearful that Meg would change her mind. Decide she didn't want to go on this... date with him. But when she asked him if he knew what people do on dates, he actually shrugged.
"No, I am not aware of what people do on dates. Do you? You could... teach me about what people do on dates." He assumed there were certain things they had to follow along with, specific protocol. The amount he knew about humans and their ritual dictated that there were specific roles that each person played amongst their different stages of mating. He didn't even think about money, although he knew he could easily procure it. He'd been able to when he attempted to go shopping for the bunker, to try and get himself back in the Winchesters (Dean, especially) good graces through food stuffs and porn.
When she began off toward their intended destination, he looked after her for just a moment, but quickly began to follow, not needing to take too large of steps to do so, thanks to his advantage over her.
"Where are we going?" He had no idea where most people went for dates or what the standard fare actually was, although he had a vague knowledge of what humans did on dates, often involving a meal of some kind and watching a movie. But, as it seemed, he and Meg didn't look to be heading in the direction of where either of those activities lie.