6pt125 ,
The striker should be worked on a 5 Degree, just off of straight up and down.

I would think a finger nail file would be ok for Glass Calls but Slate and Aluminum you don't want to make to big of friction groves as it will make it hard to work. The Conditioning is only taking dirt and finger oil from the surface.

Striker styles run differently , some tips are flat or just off flat. Some have a mushroom shape to them. This depends on the users preferance. The mushroom shape seem to be more common and easyer to purr with...BT