This is my 2nd time to this class, and I've had a blast both times. The location is clearly designed for these types of classes, with like 8 rows of 6 bags hanging in the middle of the room. I've had two different instructors, and both have given me a great workout. There's a combination of punching, ab work, and cardio mixed in. In terms of what you need, I believe you can borrow bags, but will have to buy your own wraps. I brought my own, so I can't verify that. I will say that you should make sure you cool down after the workouts. They don't really spend a lot of time doing that. Also, try to be towards the middle, as the instructors often give their instructions near that section so most people can see.
The instructors come around to help you if you need it, but don't discuss technique as much. However, since I've been to various kickboxing locations, I didn't feel lost.