PHP/AJAX Loading of Random HTML file (or Post) from an Array in a Page

Ok, I’m going to do my best to explain this, but please feel free to ask questions and I will be happy to elaborate.

I am trying to have a page that loads 3-5 HTML files or posts randomly each from an array of files/posts. I’m not sure if this is doable using custom post types or categories, but if not, HTML files are fine, too.

So this is what it would be:
Body
Header
Static Content on Page

1. Loading Container A: Loads a file/post from array of (A1, A2, A3, etc.)
2. Loading container B: Loads a file/post from array of (B1, B2, B3, etc.)
3. Loading container C: Loads a file/post from array of (C1, C2, C3, etc.)

Static Content on Page
Footer

On top of loading these files/posts randomly, I would like to trigger their loading via a button trigger. So, all files/posts loaded into Container A will include a button trigger that loads Container B. And Container B a button to load C, etc. so that they load down the page, triggered by the Loading Container above.

Is this insane or does this even make sense? I greatly appreciate the help in advance.

Note: this would only need to occur on one page, the rest of the site will be standard WP pages and posts.

Thanks in advance!