Best way to organise content
First off, this isn't really a question that has a single correct answer.

It is really up to the site builder as to how they want it to work and it depends greatly on the use cases of the site and any business rules related to the content.

As such, it isn't the best question for a site like this, however I will say a couple of things:


Having thousands of taxonomy terms is ok if your content requires it. You might have a thousands of taxonomy terms and tens or hundreds of thousands of nodes. That's fine.
The second option you mention doesn't sound like a good idea. Mainly the use of fields as blogs etc. doesn't sound right conceptually. Plus handling revisions, permissions, comments for blog posts etc. is going to be a hassle to say the least.
The first option mentioned doesn't necessarily have to have the term page as the topic homepage. It could be done other ways, like having the backgrounder node as the topic homepage or using a views page with arguments to be the homepage.
Another possible solution is to have the backgrounder node be the home page and link everything to that via an entity reference field, removing the need for taxonomy at all.
As for laying out the home pages, consider using the panels or context modules combined with views.


These are not nearly all the possibilities, there are a bunch of other ways things could be done, so you can see you will not be able to get someone to give you a definitive answer.