Well, let's see….the regular conformation starts on Friday, and it is usually just the dog classes; and then on Saturday it is just the bitch classes; and then on Sunday it is Best of Breed (so, the finished Chs, and the winners dog and winners bitch, and field dog, field bitch, and the winners of the veteran classes)....followed by the brace competition and Stud Dog and Brood Bitch (kind of judging the breeding ability of the parents). So, to answer your question, yes, it is broken into several days because of the number of dogs. A judge is only allowed to judge so many dogs in one day. It is all the same show.
There is Sweepstakes competition on Thur which will be for puppies and veterans.
Some people dress up for the Top 25 exhibition (Wed, I think?) but most people go casual. And most people dress nicely for the banquet. I think the rest of the time it is very casual, unless you are in the ring. Nothing is formal, unless you are showing in the Top 25.
What to bring? Make sure you bring comfy chairs to bring to each venue, and if you have a pop-up, or outside umbrella, you could bring that...it is great to be able to make your own shade. A cooler is useful to, so you can keep some drinks and bait next to your set up ringside. There will be some down time, so that you could site see in the area, the Horse Park is awesome, we hope to find some time to go there.