Astoria showed up because she told Mac she would and she was curious. If there were roller blades instead of roller skates, she probably used those, mostly because she's more accustomed to ice skating, and roller blades are, to her, the closest thing to ice skates. She would have been friendly with others there and just taken the whole thing in. Unless asked, however, she probably wouldn't have stayed all night, and she'd have taken breaks in between skating for snacks and drinks.