Looks nice. That knob on the back may have to do with adjusting buttonhole stitching to make sure it is even on both sides.
The bottom dial on the right may have a setting on it for cams. I have a model 1803 that has a "Cam" setting.
That little yellow case normally contains parts to convert your machine so that it will chain stitch.
Didn't see a manual at Sears Parts Direct, so eBay may be your best bet.
Here is a threading diagram:
http://www.sewusa.com/Threading_Diag...ng_diagram.htm