A: The bachelorette party is one event where the hosts aren't necessarily expected to foot the bill for everyone. In fact, the hosts are often more "organizers" than traditional hosts; they take charge of getting a group of friends together for a night out. Typically, everyone chips in to cover the cost of the bride's food and any drinks, since she's the one being honored. Any arrangement you come up with for funding the evening is fine—just be sure that everyone knows what to expect before the night begins.
If the event is more of a classic party being hosted by one or a few people at a single venue, then the traditional rules of hosting apply: the hosts covers all of the costs: food, drinks, decorations and any party favors.
While gifts aren't usually given at bachelorette parties, it is popular to give the bride an inexpensive little something to commemorate the evening—usually a token like a T-shirt (or perhaps a more intimate garment) saying "Bride-to be" or "Taken." In this case, the group usually either decides on a gift together and all chip in, or one person takes the initiative and pays for it herself. —Anna Post, The Emily Post Institute