The crank does not separate..., at least not on purpose.
The rod obviously does. This is to accommodate assembly and service of the bearing/connecting rod which is a needle roller design comprised of individual needle rollers..., probably about 30 of them. They may be contained in retainers as two 'halves' in this application. I'm curious myself. Maybe someone who knows will chime in?
Here is an old IPL that may be helpful. The above is illustrated on page 2.
As for filing points, go easy with whatever file is chosen. I would personally consider a raker file a bit aggressive for the task, but whatever is used should be followed up by fine grit paper or cloth to achieve the best finish surface area results for your efforts. A half-assed effort will yield half-assed result every time.
Good luck.