At one time, I was a school nurse and did scoliosis screening. So, I know how the diagnosis can really shock and surprise people. Hopefully, your daughter's treatment will be as successful as people I am aware of.
WDW does put warnings on certain attractions. Their 'basic' warning says that people with neck or back problems should not ride these attractions.
You can look at the park maps for the attractions with warnings - they are marked with a red triangle on the map and also on a sign at the entrance to the queue.
For
Epcot here are the attractions with warnings:
- Mission Space - the more wild side is the Orange Side. Both the more tame (green side) and the more wild (orange side) jolt you around, mostly forward and backward. The Orange side also has a centrifuge action that spins the entire ride cars.
- Test Track - this is a simulation of the testing that cars go thru before manufacture. It includes swerving, sudden stops and sudden acceleration.
For
Magic Kingdom:
- Splash Mountain - you go down several drops. The largest is very long and steep and you may get jolted at the bottom.
- Big Thunder Mountain Railroad - a fast, winding roller coaster
- Tomorrowland Indy Speedway - the problem here is that these are gasoline engine cars, many of them driven by children. The cars have hard molded seats and you can get rear ended by other drivers. The hits can be quite hard.
- Space Mountain - will be opening back up in November after renovation. It is a roller coaster
- Goofy's Barnstormer (this doesn't have a triangle warning sign on the map, but does say that pregnant women should not ride, so it is not totally tame. It is a short roller coaster - about 90 seconds)
For
Disney Studio
- Star Tours - this is a simulator ride of a spaceship being driven by an inexperienced space pilot. There are sudden changes of direction and you can get bumped around quite a lot.
- Rock N Roller Coaster - this is a roller coaster, although a very smooth one. It does some inversions.
- Tower of Terror - the idea is that you are on a spooky elevator that leaves the elevator shaft and goes into the Twilight Zone. You are sitting on hard seats and go up quickly, then back down, up and down a random number of times.
For
Animal Kingdom:
- Kilimanjaro Safari - this is a "2 week safari" in "a game preserve in Africa," so it is bumpy. You are going over simulated dirt roads and can get jostled around a lot.
- Kali River Rapids - this is a ride down a rapids in a rubber raft. Because it is free floating in a channel, you can get sudden drops as the raft goes thru the rapids.
- Expedition Everest - a roller coaster
- Primeval Whirl - VERY rough. This is like combining the Teacups with a roller coaster. Smaller riders (or those who can't brace themselves well) can get thrown around a lot.
- Dinosaur - this is a simulator where you are riding in a Jeep like vehicle through time. It is very rough.
Soarin' is one that people frequently think has warnings, but it doesn't. It is actually a very gentle ride on a simulated hang glider.
Most of the rides have molded plastic or molded fiberglass seats, which may not be the most comfortable for your daughter to sit on.
Spaceship Earth and Haunted Mansion do not have any warnings, but people with neck or back problems often find them problematic because at one point your ride car will turn around backwards while it goes down a hill with you lying on your back. Some people with back problems find this uncomfortable because their back is resting on the hard seat. The backwards area is fairly long, but not jolting.
You can find a lot more about individual attractions here, on another part of the DIS site.
This is a link to the MK page to get you started, and there are pages for each attraction, with pictures and in some cases, even
youtube videos.
When you get to the parks, you can ask CMs at the entrance questions about attractions. If you are really unsure whether or not she will be able to ride, ask the CM if someone else in your party can ride first and get an idea about how the ride is. Even if she can't ride, she should be able to come thru the lines with you (sometimes the queues are quite entertaining, then leave just before the rest of your party boards and wait for you at the exit.
If she needs to take the brace off, you can do that in First Aid in any of the parks. I would not suggest taking it off for attractions - with the getting it off, walking back to the ride, riding and then getting it back on, it would consume most of the hour.
You should talk to her doctors, but if it was my child, I would use the 1 hour out of the brace for activities like swimming (and depending on her curve, the doctor may allow it off longer for an activity like swimming because the water supports your weight and swimming is good exercise.)
( We are about to get her the Spinecor brace which is a newer brace to the USA, it is made in Europe. Her back is beginning to ache her all the time so I am really hoping this will give her some comfort. I know it is going to take some getting used to. She is already quite head strong with regards to the comfort of her clothes, to put it nicely - lol. She doesn't like anything tight, so this should prove to be a challenge. Although, she has been asking for the brace because she knows it will help her back. We're hoping it will make it so we don't have to have surgery done, at least now while she's so young. 
But I know my girl, she wants to go on ALL the rides. 
Most research I have done says at 10 - 12 months they can usually do this. Still getting other opinions, more specific to amusement park activities seems sensible to me.
