[Plugin: Custom Fields Template] How to add dropdowns with post titles dynamical

Hi,
I use the custom fields template plugin. For my pages I would like to configure a dropdown field as custom field which does the following thing:

1. The dropdown shows a list of posts/custom post types
2. The list is categorized: 1st level is the category, 2nd level the post title

I can then select a post and the ID is stored as custom field. I Want to use that custom field value to display on my page.php content of the referenced post, e.g. for a “Read also this…” part.

Is this possible? How could I managae something similar otherwise…