For example: Prejudging is at 10 - how long does prejudging in a contest like this last?
Also, there will be advertising booths. Are they open before and after prejudging? Or only during contest times?
And if I go by myself, and have to go get a drink, how can I hold my seat?
Prejudging can last a number of hours. Duration depends on the number of competitors, efficiency of the judges, and how organized the shows promoter is. I would expect prejudging to last at least 2-3 hours. You find people will come and go through out the prejudging. If I know all the women's divisions have been on stage I leave. It looks like it is open seating.
Notice the photo in the middle? I looks like they have the first 6 rows reserved so go early to get a good seat. I cannot recommend this enough. Your proximity to the stage can open an entirely new dimension of audio as you can hear the women breathing and straining as they flex. With the acoustics of a venue like this the subtle audio nuisances of the competitors on stage might not audible above the ambient noise. Regardless, closer is definitely better.
Relax, be cool, and have fun. The crowd will not just be people from the fitness industry there will be competitors friends and family so you will blend right in. If the opportunity presents itself tastefully complement a competitor. Female bodybuilders push the boundaries of social norms and providing them with positive feedback is generally well received. However, be respectful. I don't know if this is true but I heard Tre from femflex was knocked out by Nikki Fuller after he said something inappropriate to her at the Jan Tana Pro.
You might also consider checking out the NC state which is a few weeks earlier in Greensboro. I looks like that show might attract more competitors and is at a theater venue which is much more enjoyable from a spectator point of view. Better lighting, sound, and seating. Here are a few pictures from the North Carolina State Championships as well as the venue.
So back to your questions....
Booths will be open during prejudging and sometimes staffed all the way through the evening show. As far as saving your seat this is where it can be critical to talk to people around you. Find out who they are cheering for and cheer for them too. This is a very fast way to make friends. Ask them to save your seat if you need to get up and do the same for them. You might even find that female bodybuilder you were cheering for coming into the audience to talk to her friends and you get introduced.
Some things to consider...
Do you want to bring a camera?
With a camera you can capture the event however, you are detached from what is happening. If you're taking pictures people are less likely to chat with you. Personally I've had better times when I've not brought a camera with me.
How to dress.
Most people wear casual clothes or workout wear. Years ago I went to a competition right after getting off work wearing a suit and tie. I arrived a little late after the contest had started and sat towards the back trying not to disturb anyone I found an empty row. Just a few minutes later out of the corner of my eye I noticed a figure moving down the same row I occupied. My initial thought was one of frustration. I picked the row specifically not to disturb anyone else and here was this person that didn't have the same courtesy. Instead of expressing my frustration I decided to focus on the show because the women were coming onstage. It was an impressive line-up and I was suddenly shocked by a woman's voice saying "Did I miss anything." "No" I replied. She sat down next to me and I instantly recognized her as a woman I had seen compete before. I was very nervous but was able to keep it together. We talked about the competitors and afterwards she introduced me to a friend that was competing. When we left the contest she invited me out for a drink. Sadly I was only 20 so that drink never happened. So take what you want from my story but I've found when your among people in t-shirts and sweats looking classy can set you apart from the rest of the crowd. Perhaps that was why she sat next to me.
On the website ticket page there contact link for questions.
http://www.eventbrite.com/e/2016-npc-the-charlotte-cup-bodybuilding-championship-tickets-19548722756I don't know why there are two different prices for the prejudging and evening show. Perhaps early bird seats are available until they sell out?
If you can get reserved seats do it.
I hope this has been some help.