I'll think on this some. But just to start a discussion that others can join in:

1- the lens is probably not fast enough to use available light, so use of a flash is probably needed (someone jump in if you know more about this Nikon camera and what ISO it can do well

2&4- Since the judges come to the bench, the light is going to be different in every situation...that is a strong driver in shooting RAW. If this is anything like showhalls in the US, then you may be directly under a sodium light for one shot and in the near dark for another.

3&5- If you are looking to do this 'better' in the future, the first impression that folks have of your work is very important...they WILL remember. So 'half decent' might achieve your immediate goals but end up biting you in the rear in the longer term.

More later........and, thank you.