New to WP – Need advice on blog stucture

Hi,
I’m pretty new to wordpress and I would like ask for some expert advice on the best way to do my thing.
I’m trying to update my blog with new pages presenting my games collection.

Here’s what I would like to have on my header with a dropdown menu :
Home/ : shows blog (as it is now)
Collection/Manufacturers/System/Origin

So far I’ve created an empty page for ALL of the planned categories I’d like to sort my games pictures in. This is how the dropdown menu is done right now. I’ve created, with “Types” plugin a Custom Post Type called “Collection” and a Custom Taxonomy called “Collection Categories” (sega, nintendo etc…) as well as a new page template.

This is pretty much where I stand now. I’m not too sure that the way I’m trying to build this collection page is right and about what to do next.

Ultimately what I would like to do is as follow :
When creating a new entry in my collection, I would like it to be posted both into it’s proper child page but also in all of the parent pages.

If anyone could give me some advice or point me to any tutorial that explain how to do something like that in order get me out of this deadend, it would be very helpfull.

Thanks ??