IMO black will make them look deeper flanked but if you are to leave it white and paint it with ultra white after fitting, the brightness of the paint will stand out against almost every background giving the deep look. And by having some white the calf will stand out to the judge. It's all...
To be honest I don't think any questions are asked. I may be wrong though. Unless there is an interview process but I've never heard of one. Best of luck to the kids, it's a great experience.
From the pics it appears he has some issues with his hocks turning in on those rear wheels. He will need a lot of hoof work to turn that around. just my opinion.
In your personal opinion can you put yourself at a disadvantage by "over fitting" a calf for show? Do some judges become skeptical of whats under the perfect fit job?