Having more than one host license on a Pro account allows each user to schedule and host meetings independently of one another. With just one licensed user, that account could only have 1 meeting running, but an account with 2 licensed users could have 2 meetings running concurrently of one another.
Thus, a Pro account with multiple licenses would be good for a small business that doesn't need the minimum of 10 licenses the Business account requires, but still has a few users that need to schedule and host their own meetings without worrying about others running meetings at the same time.
As for that last question, yes, anyone in the club can be the host if they log in with the club's account, but you cannot have everyone signed-in to the same account at the same time. Also, its not wise to share login credentials with everyone, as that can cause confusion, double-booking, or accidentally deleted meetings if there are too many proverbial cooks in the kitchen.