It's true that the grind settings will make a difference in extraction rates but it's hard to predict ahead of time unless you've brewed with that grain at least once. I routinely add a pound of extra pale grain to make up for this but it's still a bit of a crap shoot. I wouldn't worry about adding extra flavoring malts, since they generally make up a smaller portion of the mash and from what I understand their contribution isn't as dependent on crush quality. Regarding adjusting wort gravity after the boil, if you're gonna add something I would add dry malt extract, however ideally you should avoid that by adding extra grain at the start. I monitor my gravity during the boil (possible with a refractometer) and control final gravity by adjusting boil time.
Like the others, I would say don't sweat it. If you really want to be precise add an extra pound of pale malt and then if you overshoot your gravity due to the extra malt you can compensate by adding distilled water.