Off the top of my head I can't think of any way to do that, but that doesn't mean it can't be done.

What version of b2evolution are you using? Before anyone can even begin to come up with a method for this that would be required info yah?

And wow I'm curious: why would you want to do this and what would happen if a visitor clicked the name of it in the categories list?

v2.4.1

I'd like to use the posts as an easy way to add info to the site but while not adding it above the info/posts already there (since the info I want to add is not the primary info I want people to see when they first go to the site), so I figured if I could create "hidden" posts that can only be accessed when someone goes to the post directly it would be great. Kind of like adding the new posts as "references".

I suppose you want to use this blogging program as a real CMS. You can use the bloggingtool B2evolution as a CMS, but then you need to have a lot of 'workarounds'.

You could 'manipulte' the dates from those reference posts and then those posts would not be published on the homepage.

You could create a different homepage that would not include the blogs with the reference posts.
Then you just manually put a link to the blogs that are not included on the homepage

You could consider to use Drupal. That is a CMS where you can blog with.

A couple of options exist. Back-dating the stuff that isn't that important is an easy one, but not the easiest. On your Blog settings -> pick a blog -> general subtab select "Ascending" from the list for post order, then make your most important post first with subsequent posts being less important. That's probably the easiest. There are other ways I guess, but I don't know 'em.