i am a 4-h leader and i think you should do one thing and do it well. I have a 10 year old member who did one of those boards on scrapie. It was well recieved at the state fair and won best poster on goats. It helped explain why his goats were seperated from other goats with a solid partition. It's amazing how everyone has a scrapie tag and no one follows the guidlines for scrapie eradication.i might suggest you not try to hit so many points on one project board but rather narrow your focus and treat each point in more depth. I have seen excellent presentations done on just milking, or grooming, or labor and kidding etc.
I think maybe kidding would be a good subject and put together a kidding kit to go with the poster. That way you can enter two classes with the same materials.
You could do the same thing with hoof trimming