I think the reason no one is replying is because your plan seems, uh, excessive. Outside of slugs, scopes on shotguns are for people with vision problems and people who spend more time reading magazines than actually hunting.
I wouldn't mess with laser sights at all. If you're dead set on some sort of scope set up just put the thing on and sight it in. You do not need to account for bullet drop in shotgunning, outside of slugs.