[tlhIngan Hol] x nuq vs nuq x & 'Iv x vs x 'Iv

This is a rather simple thing, but unfortunately it's something that confuses me.. I want to say "what's this thing ?". Are the {nuq Dochvam ?} and {Dochvam nuq ?} equally correct ? And if not, what's their difference ? I want to say "who are you ?". Are the {'Iv SoH ?} and {SoH 'Iv ?} equally correct ? And if not, what's their difference ? ~ bara'qa'