A bit OT but since you brought it up:

I tried to equip my spit with tracers to, at least for the four outboard guns.

Can you help me how to do it?

And also how to use it in quick mission?

I saved my customized ammo belt with the name Angepasst. I load this during quick mission (usually only empty or Angepasst available at the quick mission configuration screen). But all that I get seems to be the default belts ...