As far a dropframe formats go I believe that dropframe TC is a display property only - to cope with the fact that NTSC is not truely 30fps but 29.97. So the TC is accuratly counting H:M:S at 30fps , whilst dropframe gives the realtime equiv. it's explained better linked above.

Update: Another gotcha about EDL format is that TIMTOWT specify dropframe mode.. but that should be the responsibility of a parser , hmm, creating work for someone now , aren't I? (rhet.)