1. Is there a difference between Region 1 and Region 1 N.T.S.C.? I ask this as there are different descriptions of DVD bought from American sites - some have N.T.S.C. added to their descriptions where others do not.
2. Will the fact that I have adapted my DVD player to Region 0 mean that I will be able to play ANY DVD bought from abroad irrespective of whether Region 0 has N.T.S.C. after it or not?
that's what has happened to mine, I can play NTSC DVDs on it; but it could be different for different models. I'm not sure if the Americans actually do PAL DVDs, so NTSC may be the default option and not always mentioned.