Today’s Saturday Stumper

About today’s Newsday  Saturday Stumper, by Matthew Sewell: 24-A, seven letters, “Oh my!” My commentary will be 1-A, five letters, “Of few, sharp words.” And that’s 12-D, ten letters, “... no joke!”

For me, today’s puzzle is far too opaque. I looked up many answers — funny how that gets easier once you start. So I found little joy here, but I did like 29-D, ten letters, “Mobile library setting.” My first guess, and a well-founded one: APPALACHIA.

No spoilers; the answers are in the comments.