Attaching images to the main blog is mandatory and only the inserted, not attached, images appear in the blog post. Any non inserted but attached images will appear in the gallery and any attached images to that main blog can be used as a cover image for the main blog. Nowhere else aside from the main blog can those images be used unless you upload them repeatedly to each blog entry and or every page.
After you make your main blog you can make blog entries. Each entry is like a book and your main blog is the library. Since each blog entry is like a book it is treated as individual from the main blog.
Every blog entry can be indexed through pages like a table of contents and each section you make can be divided by pages. In my grow journal my pages are below
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The overview is the blog entry and everything below is a page I made. Images added to pages don't go in the gallery of that blog entry unless you attach them to the blog entry(overview) itself. The other issues is that per page whether it's a page or main blog or main entry, everything has a universal 25 image limit.
There is a tutorial for this whole thing but it's being tested before it's publicly released.
You can go through my blog if you want to get a clearer idea.