Newbie questions. Does it damage a suppressor to fire regular ammo through it, and does it suppress it materially if that's what you do?
No it shouldn't as long as the suppressor is rated for it. Some multi caliber units have warning about using full tilt rounds of higher calibers in them.
It reduces the muzzle blast noise to a degree, but the supersonic 'crack' will still be quite loud.
When I despair, I remember that all through history the ways of truth and love have always won. There have been tyrants, and murderers, and for a time they can seem invincible, but in the end they always fall. Think of it--always.