Dynamic text display methods and storage in Unity

I am hoping to port my gamebook engine from native Android to Unity for ease of multi-platform publication. I chose Unity because several high profile game book publishers such as Tin Man Games have been using Unity for their engines and the games look fantastic. The objective is to create an engine that can render a book (2d or 3d, doesn't matter much), read in a large amount of text and change the text displaying on the pages according to user input.

I am looking for hints and maybe a push in the right direction on how to accomplish these things in Unity:

- Preferred way to store large text assets in Unity that can be utilized and picked through at will. Are txt files viable for this task?
- How best in Unity to **display large strings of dynamic text that may need to be broken across multiple pages depending on user's display size**. GUIText seems ill-suited for this task during my explorations so far but tutorials or even questions relating to large text seem few and far between. Most questions I have seen regarding books in Unity assume you're using pre-rendered textures for pages rather than dynamic text.
- This text will be displayed on top of a page. I assume there's no reason I can't use a quad for each page, add the background page texture, and then overlay text onto it somehow? Changing the text as the user flips the page.. That was what I was originally trying to do with GUIText. Most of my confusion stems from how to integrate this dynamic text into Unity and display it on top of my quad pages (assuming using quads was a good idea to begin with).

Thank you very much for taking the time to check out my question!

Example of the ultimate desired behavior (fast forward to around 5m25s or so):

(example:

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