I know that, officially, the shade of blue is supposed to be "any shade of blue that is lighter than the blue of the Union Flag." Many people (including the office of the Lord Lyon) over the past several years have suggested standardizing the blue as Pantone process color # 300. It's not technically "official", but most flag makers have started using it anyway (BTW, the Pantone color of the Union Flag is # 280, which is much darker.)

Carolina,
No, those flags aren't "official." They're just a combination of various Scottish images (although I've seen some that were really nice.) Sometimes you'll see a Saltire with reversed colors (blue cross on white field) with a Lion Rampant in the middle. That's the official flag of Nova Scotia, which used to be a Scottish colony.