You can park right at the port and there is no need to prepay. We just did it. There was a lot of talk about prepaying and unless you want to park elsewhere and shuttle to the cruise terminal, then go ahead. The parking garage is literally maybe a half a block from the entrance to the terminal.
I agree the info is sketchy at best, but I called the parking garage and they said you can park there and no prepay. I will say that they have a standard price that was 200.00 and we were on a 12 day cruise and that was what we paid.