Ok as I wrote before it is most important that we keep the terminology straight or else we'll be talking past each other.
There are 4 main parts to Aperture, the Library, projects, albums (smart & regular) and folders.
The Library holds all the other parts.
Projects are the main items in an Aperture library. They hold the physical image. All images imported into Aperture HAVE to be in a project. An image can only be in one project.
Albums hold references to the images in the projects. Think of them as pointers back to the project image. Images can be in as many Albums as you want there is no restriction.
Folders are containers that hold the other parts, projects, albums, and folders.
So what you wrote about in regards to 2013 makes sense, you have a project with albums under it. What you wrote about 2012 is difficult to understand because those images in the 2012 folder have to be in a project somewhere. So the question is where is the project that holds the 2012 images?
The reason you can;t drag the images from the 2012 project to the 2012 folder is because as I wrote previously folders do not hold images they hold other containers.
As ou have a 2012 project started the easiest thing to do is to locate all your other 2012 images and move the ones not alredy in the 2012 project then make the smart albums under the 2012 project.
And also keep in mind that while there is no software restriction on the size of projects some users have reported better perfomance with smaller project sizes. As you say you only have around 800 or so images in a year I don;t think that shoul dbe a factor but it is something to keep in mind.
regards