Paul, your TA can arrange this. You need to file a form with guests names and passport numbers or drivers license numbers. The form needs to be filed at least 30 days in advance. When you get confirmation, send a copy to your guests and keep a copy for yourself. Of course, since they are driving you to the pier, you really don't need both copies.
I don't think they will charge you for lunch for your guests. They did charge us but then they had a 100 guests in San Diego. We also arranged for cheese and cracker trays and shrimp cocktails in the cabin before lunch.
It was great showing off the Voyager. Since then, we have gotten my father to cruise once on the Mariner and he is now booked on the Voyager; primarily from getting a chance to enjoy the ship while in port.