My DD's have gone for the past 3 years, in fact my youngest is there this week.
First of all it is a very well run camp with great counselors, coaches, gymnastics and oh yes the food. Even my older daughter who is picky said the food is awesome.
On Sunday they will split you up into workout groups. This is done by size and skill/competition level. The screening is basically what others have said-hardest skill on floor, bars is cast handstand and clear hips I believe. The workout groups are nice and small 6-8 girls I think.
It is very easy to make friends. You will get to spend time with your cabin mates but your work out groups will be with some different girls as well. There are many fun planned activities as well as time on your own.
They will absolutely not allow any electronics (phones, laptops, iPods, ereaders) so don't bother trying to bring them.
I hope you have a great time, I'm sure you will!