Fun is what it's all about. Too bad about forgetting photos, but I know the feeling when it's crunch time. I would have scored your rib photo a solid 7 on appearance (possibly an 8 in person). Appearance is based on impression only, things like arrangement, garnish, fullness etc. are not considered.
Don't worry about your finish when compared to the overall ranking. It's better to rank yourself with other new teams. The organizer or Reps can tell you how many teams were first timers, and if you ranked ahead of some of them (or most of them), that's a good start. And don't beat yourself up over the score sheets, two or three 8's in a field of 9's can really have an impact. One or two 7's will really lower a ranking.
A ton of food is correct. The ratio is one judge for each team. in other words, 30 teams need 30 judges (and we all hope they are certified judges). If there are uncertified judges, they get a crash course in judging, and are limited to one per table. Now here is the deal..., each judge takes about 24 to 30 bites over the two hour judging time. All the entries are tracked so that a certain table does not get more than one entry from any one team. Also, of the 6 judges at each table, the lowest score is thrown out.
What category was your best and worst? And did you get any comment cards? This will help for the next contest.