Custom Posts, Sortable, Saving - an idea I need help with.

I am working on a theme for a client and have an idea for a feature but don't have a clue where to start with it.

The theme has a horizontal slider menu at the top of the home page. What I'd like the end user to be able to do is to select which pages are on the menu without having to know anything about code, etc.

The UI I'm seeing in my head is this:
- Use a custom post type for the menu info (use the "title", "excerpt", featured image (with cropping capabilities), and a custom field for the URL that it would be pointed at. Would like to have it to where they could click on which page / post / etc. that the menu item would be pointed to.
- Doing something like the regular WP menu creation UI where the user can drag from a list of the available menu items into the 5 available spots for the horizontal slider menu, which would then save both what menu items are in there as well as the order they are in there.

Not necessarily looking for someone to do this for me per se, but wondering:
- is something like this possible?
- how hard this would be
- is something like this already out there where I could take a look at it?
- are there plugins that might get me at least part of the way there?
- anyone have any other tips / thoughts?