To start with I would use your book settings from hypertherm.
Then as far as how I determine some of these other settings would be what I’m cutting and what the geometry is like.
If I only got small holes while I’m constrained for what my lead in like leading radius can be. I normally on small holes don’t do any lead in. I’ll do a lead in radius just slightly less than 1/4 of the hole diameter with 160° radius. For open contour geometry there would be no lead in radius or lead in length or Pierce clearance. For closed contour geometry two times the Keef width is a good recommendation with about a 60° lead in and maybe a .025 lead in radius. As long as it doesn’t leave a divot it’s long enough.
@criptosis btw Welcome to The forum