Does the hotel offer $6 per day parking for cruise guests only if guest is booked and paying hotel for a stay (i.e. to include the days/nights of the cruise) or can a guest pay/stay one night and go on a three-four day cruise and still park @ $6?

The shuttle pay and the parking in hotel is free

Park, stay one night and pay parking for length of cruise, get on shuttle to port ($4 each way per person), enjoy your cruise, shuttle brings you back to hotel, get in your car and drive home. Best experience ever! Hassle free! Love this place!

Contact hotel as fares may change.

Not sure but I believe that you can stay a night there and use the parking afterwards for 6$/day

Contact hotel and ask