as to the question who sings which line I have found this:
Verse 1 he, verse 2 she, verse 3 he, verse 4 she and verse 5 he (also the last line!). The between lines (nu ja ja, nu..) are sung by the opposite sex, respectively. So from the beginning, in Sorcha's post, the gender singing per line is:
M F M F / F M F M / M F M F / F M F M / M F M F.