A few important things to remember:
No cars. Everything's close together; have your characters walk. Bike, if it's far. There are carriages, carts, wagons, and so forth; also, lots of boats. Some pets will consent to be ridden; Unis are most obvious, but Skeiths, Eyries (which are very large), and any large pet will do.
No phones. Use neomail. It's instant. Within the SNRPG, neomails are depicted as little gold envelopes with white wings (as seen in the Neomail Addict avatar). You can also use the SN communicators.
Faeries change size. The ones that interact with users and pets often (Illusen, Jhudora, the Rainbow Pool faerie) tend to appear as human-sized. Kaen appears as about 30 cm (1 foot) tall, as do the majority of faeries who keep to themselves. The Faerie Castle and the tourist areas of Faerie City are on a large scale; residential areas are smaller.
There are pets. Lots of pets. In fact, there are more pets than users. If you meet a shopkeeper, watch a news commentator, listen to a band . . . chances are they'll be pets. Use pets as teachers, as coaches, as any sort of extras.
Borovan Day = Christmas. More or less. December 25 is the Day of Giving, but that's a more minor celebration, and not religious in Neopia. Since the major religion in Neopia is Adam-and-Donna worship, the winter-solstice-time-celebration is Borovan Day, December 20.