A fine job, you did, between you. Some lines have more than one possible sense if you don't look for the context. But the final result looks very good. Three remarks:
(1) I think he is singing the last line (in a sense of 'If you say no, I tell you that I don't like you either'), but there is nothing in the lyrics that excludes Joe's interpretation.
(2) I think, Ebbie's right and 'nu' is 'nun', here best translated by 'well'.
(3) I haven't found Kraenzelkraut yet in my largest dictionaries. Perhaps that is a local name for a common plant. But whatever that plant is, it is to be picked for the bride's wreath, an outdated German custom. And 'pick that plant' has definitely the meaning of 'prepare to marry' or in Joe's translation 'go pick somekindaplantformakingthebrideswreath'