I'm working on a membership site in WordPress and I want a specific group of my users to be able to have access to a page I create, but then also have admin access to this specific page and be able to add items as they see fit to this page. Is it possible to give admin access to a user but restrict it to a specific page or set of pages?
I know this question is kind of off-topic but I need to come in and say firstly don't add anybody... anybody....
as admin on the site... At that level they can do everything you can do, or probably a lot more if they actually know what they're doing :-p It's a good way of getting your site hacked, compromising data and filling a few thousand more inboxes with junk.
What you'll want is to add them as an editor, which doesn't have nearly the same level of permissions as admin.
Secondly welcome to WPSE - please do give this a read.
Whilst asking for recommendations for plug-in's is off topic it sounds like that's probably the level you were wanting help at you may want to give this page a read. It recommends Capability Manager - sounds like what you're after