So, isn't declaring the High Speed fuse then sufficient for PicBAsicPro Compiler, as I wrote in my program?
for this chip yes
You say that setting OSC has no effect on PULSOUT but that the resolution depends on the crystal used.
?
its a legacy [old ] command, it does not use the OSC define in its operation


What is the point of defining OSC
non legacy commands do use the OSC define in their operations

And considering what Mpgmike said above
is incorrect and out of context for that chip



(Theoretical resolution at 16Mhz should be 2.5 µsec I think).
So the PIC would work well here at 16Mhz
thats it