A simple 'related posts' plugin that lets you select related posts manually instead of automatically generating the list.
People who want to list 'related posts' in their blog posts or pages, and want to choose the related posts themselves, instead of having a list generated automatically like other plugins do, using weird algorithms that often create comical results.
Data is stored in the existing postmeta table in the WordPress database. No additional tables are created.
As many as you like, there's no limit.
That's true, it isn't ideal for large blogs. This might get improved in future releases, feel free to submit ideas.
With version 1.1, all data remains in the database when the plugin files are deleted through the plugins page in WordPress. So if you accidentally delete the plugin, or if you decide to install it again later, your data should still be there.
Yes, it is again actively maintained.