Okay, I'll keep going on the part I know about, and hope someone can answer the original questions
The braiding is usually done by the Goofy Pool. The sign up times vary, so look in your navigators if you want it done. The odds of getting in without an appointment aren't good! I typically see sign up around 5:30 on boarding day, and maybe 9 ish on the next day? Lots of the young girls get it done. Some people have complained that it hurts, so if the girl is tender headed, be sure they know that it might pull.
Different styles of braids, here goes:
Headband style is cornrows (little french braids) starting at the forehead and going back to the crown or top of the head. If you have bangs, they'll leave the bangs hanging down in front. They put 3 or 4 beads at the end of the braid, and they all line up and look like a headband. This style definitely pulls the most because they want the hair to be tight against the scalp. The rest of the hair is left loose, and can be pulled back into ponytails or any other normal style. Depending on how thick your hair is, and how big your head is the number of rows varies. My DD had this done when she had just turned 10. She has fairly thick hair, and needed about 12-14 rows. I paid $35 including tip (I think it's $2 a braid for this style).
"Normal" cornrows. These start like the headband style, but the keep going to the ends of the hair. I always think of Bo Derek in the movie "10", but I know that's showing my age! Again, this is $2 a braid if I remember right. I didn't see too many people choosing this option.
Braids. These are just normal braids, but are usually very thin. You can have them do your entire head, or just have a handful of them done. Cost of these braids is $1 apiece (again, that's what I remember, confirm the price!). When the whole head is done this way, I've heard it called "bahama braids". I actually do this myself when I'm camping, since it keeps me much cooler than leaving my long hair down.
For any of these options, be sure (REALLY, NO KIDDING) to apply sunscreen to the exposed scalp. I've seen people with blisters (usually little kids!) where this tender skin was showing! I personally swear by the Coppertone sport spray. It's clear and not nearly as messy as the lotion type for this kind of thing.
Finally, hair wraps (the original question). Hair wraps are basically wrapping embroidery floss around a narrow strip of hair, and attaching beads and dangles to it. They offer this at several of the WDW resorts. I've had my DD's done twice at Port Orleans, and I bought a Klutz book and have done it myself for her and some friends. You didn't used to be able to get these on the ship, but I saw it on the latest Eastern navigators and wondered how much they charged. The last time I saw it at WDW, I think it was something like $1.50 an inch, with an extra fee for each bead? I do remember paying about $30 for the last one my DD had done, and that was at least 5 years ago.
Hope this helps someone!