Around 24 to 72 hours depending on thickness and how humid the room is. Thick bases take longest and crack if rushed, so keep the walls even and leave it somewhere with air moving rather than on a radiator, which dries the outside before the inside.
No — air-dry clay is porous and is not food safe, which is exactly why this project is built around a small plastic dessert dish. The clay forms the decorative outer dish and the honey stays in the insert. Do not skip that part.
Rolling and shaping the clay suits about five and up. The beads, charms and paint markers are the part younger children enjoy most and can do with help. The one adult job is checking the walls are thick enough to survive drying.
Paint once it is bone dry, then seal it — sealing is what stops the clay absorbing moisture. Wash the plastic insert rather than the clay dish, and keep the finished piece out of water entirely. On that basis it lasts for years.