Re: Captain for charter?
If the "learn to sail" course is touted as being all that's necessary for you to bareboat charter, then they had darned well better be willing to let you charter one of their boats the following week. Otherwise they are clearly misrepresenting their course!
A captain, as mentioned, stays on the boat. Cost is typically somewhere between $150-$200 per day. And it is customary to tip him, in addition.