Norfolk is not a typical cruise port with year round cruises and does not have the infrastructure like at the Florida ports or even Baltimore. I was on the Magic last May when it was a total nightmare. From everything I have heard and read, there have been a lot of improvements especially with the parking. I would not worry about the lot being full. If all else fails, you can park in one of the downtown garages. They say no cruise parking but they have no way of knowing why you are parking there.
Something to consider, the terminal is on the second level so unless you can manage your luggage up the stairs, you have to wait for an elevator. There are a lot of 1st time cruisers that cruise from Norfolk and they are not familiar with dropping their bags with the porters. I've cruised 30+ times and I couldn't find the porters to take my luggage but I only had carry ons so it wasn't a big deal. I saw many people trying to manage two pieces of the largest luggage I have ever seen and it was only a 6 day cruise. That caused major slow downs for the elevators, security and check in.
I agree with not trying to get dropped off right at the terminal. I usually Uber to the port and pick the Hilton Main as a drop off point. The terminal is half a block with sidewalks and crosswalks, sometimes even a police officer directing traffic.