This is a great workout and fun class! The class is only about 1/3 bag work. The rest of the class focuses on conditioning. Gloves are provided. However most people seem to have their own wraps, the trainers mentioned they aren't required but if you have them you can bring them.
Fitness Level - You've at least gotten started being active. I won't lie, the class will kick your behind (have you ever done squats holding a truck tire?), but the trainers are good working with people and the classes tend to be a mix of fitness levels.
Gym - The gym is located on the second floor, there is ample street parking and a small private lot next to the building. The entrance is located on the cermak side of the building. Be warned there are no lockers, but a small room to hang your jacket/stash your belongings. There are also a few treadmills if you want to do a little warmup before your workout.
Cost - Your first class is free! Drop in classes beyond that are $10 each, and they do have memberships if you want to go more often (I think they run about $60 a month). Any cost is payable when you get there, I am not sure about credit cards so I'd be safe and bring cash if you can.
Misc - You should arrive a few minutes early for the first class, as you will have to sign a waiver.