Debs there are quite a few books on Walt. The "authorized" book is by Bob Thomas(I think the title is "Walt Disney- An American Original"). Check out Amazon and search Walt Disney.
The problem is that many of these books either a) have some sort of stamp of approval by the Disney company or family or b) Are such unmitigated trash you can't believe any of it. You might have to read a bit of each and draw your own conclusions.
I wouldn't call it a history of WDW, but it does give a lot of background on how an attraction is 'born'--from conception to construction. There did seem to be a LOT of content regarding Disneyland Paris, but some of the 30 year old photos of WDW are priceless.
One shot that I particularly enjoyed showed a pile of building materials (pillars and such) in the middle of an empty field with a sign that read "Italy Pavilion--Some Assembly Required."
Bob Thomas's biography on Walt Disney really is a good one. I've read it a few times, it's so fascinating. It really makes me understand what the Walt Disney Company is suppose to stand for.
What about a video? I like to see that presentation of Walt when he tells all about his plans for a Walt Disney World .....also shows his plans of EPCOT.