Shots #2 and #3 seem fairly overexposed to me. With NX, if you press Shift + H you'll see any lost highlights, they can sometimes be recovered by using an "exposure" adjustment - this can get you a fair bit more detail in the over-exposed areas. (For lost shadows, use Shift + S).
With the other two shots, I think they would be better if the fill flash was reduced a fair bit - for these sorts of shots, I would normally fill at about two stops under.
Cheers



