Posts or pages and website structure.

I am working on moving a static page website into wordpress. Our current website is here: https://www.ifuw.org. My development site is here: https://www.ifuw-forums.org/cms/.

I am having a hard time deciding when to use pages and when to use posts and what the ramifications of this decision will be. I have two areas in particular where this is really puzzling me.

1. Our site displays a list of our national affiliates around the world (see this page on our original site and on my development site).

At the moment I have chosen to make the page listing all our affiliates a page, and the pages you visit when you click on an affiliate link are posts, all in the same category. A list of these posts is then displayed on the main affiliate listing page using a plug-in.

My problem however, is that when you click on one of these affiliate pages (for example), the breadcrumb navigation doesn’t show where you came from because there is no actual link between the individual affiliate post and the main affiliate listing page.

Should I make all the individual affiliates pages also? Is there a limit to the number of pages one can create before there is an impact on performance?

2. Our website has a long list of resolutions our organization has adopted over the years (see here). I am having a hard time wrapping my head around whether I should create pages to make the different year and category displays I want to have or whether each resolution should be a post and then I can create the different year or category displays with custom templates.

I realize these are two big questions, but I am really struggling with this and would be extremely grateful for any advice.

Thanks!!
Anamaria