Yes it is open and yes you have to pay $5 and yes there is a security guy there to ask all the questions.
As far as we were concerned it was a small price to pay to get rid of the luggage and have the rest of the day free to do what we wanted - especially when we turned up at MCO to see hundreds of people queueing up at check-in.
Yes $5 is a small price to pay!!!
Well done Virgin!