You are going to need a place to park all that static content, so that’s more or less got to be a post of some kind with a bunch of custom fields. Whether it’s superficially called a post, custom post type or page might not matter much after you’ve done all the hacking you’re going to need to.
The way I see it, there’s really one kind of basic data object called (behind the scenes) a post; we can divide this up into different types if we want to, and wordpress comes by default with it divided into 2 types to suit the most common use scenarios, 1 called post (confusingly) and 1 called page. No need to get too hung up on these existing distinctions when you plan to depart from a common scenario anyway.
I wouldn’t sweat the SEO angle at all as that will hang on how you set up the internal linking and the permalinks; whatever backend structure you use you can still control both of these how you want them.
I would consider using this structure:
1) Grab the Advanced custom fields plugin so you can control easily what fields go with posts and pages
2) Use the existing ‘posts’ to store your quotes
3) Use pages for any generic pages your site needs like FAQs, contact me, etc.
4) Either use pages, or create a custom post type, to store the static info for the tier 2 categories. Having it in a custom post type might take a tiny bit more work but makes things neater in the backend by separating them out.
5) Create your tier 2 and 3 categories; assign those pages / custom posts from 4) with the appropriate tier 2 category
and for the important point:
6) Hack your categories template so that it calls the static info from the first page / custom post from that particular category. Actually there will only be one, as you will only have assigned one page / custom post for each category.
7) Your URL scheme and SEO should all slot nicely into place without any hacking, just selecting the right setting from the permalinks settings place.