I don't know of a website with the info you want, but I highly recommend a book called "Walt Disney World with Kids" by Kim Wright Wiley. We have the 2000 edition, but I'm sure there's an up to date one out.
We used this book while planning our trip back in 2000 and it is great. It talks about everything from "Before You Leave Home" (chapter 1) to "Life Beyond Disney World" (chapter 16).
Don't let the number of chapters deter you. It's large print and alot of "bullet format" info.
It has all kinds of "Helpful Hints", "Insider's Secrets", and "Scare Factor" ratings for attractions/rides.
It's broken down by parks with quick guides to the attractions which list Attraction, Location, Height Requirements, Speed of Line, Duration of Ride/Show, Scare Factor, and Age Range.
It's a fantastic book. Get it! You won't regret it! I promise!
ACE