I've started back on the dermaSTAMP a few days ago.
Supposedly the growth factors that the damage causes can be helpful, but in reality I don't think anyone got much more than baby thin vellus hairs regrowing on the stamped areas. On its own it probably will not do much, in combo with AA and minoxidil, like I said, hope for vellus at best.
Never seen terminal hairs coming back from wounding.
I make it bleed too. Just disinfect properly, both the stamp and your scalp. I wash my hair with shampoo, dip the stamp in alcohol, then dab some alcohol on my temples and front too (all the areas where I am stamping). Just so I don't get some nasty bacterial infection.