ok, short answer (I'm at work)
This device began as the Singer "New Family", which became the "12". The "12K" means it was made in the Kilbowie factory in Scotland.
The simple short winder is the earlier style
The style with the "arm" began short, then lengthened the arm.
The "diagonal" unit i would strongly suspect is a non singer part put on that machine.
You can also look up the Singer 13/13K also known as a "Medium" which is the exact same machine scaled up for light industrial work.
I would suggest researching on ISMACS and then Needlebar Picture library.
If you need more details let me know.