1 tn The form מֵיטִיבֵי (metibe) is the Hiphil participle, plural construct. It has the idea of “doing good [in] their step.” They move about well, i.e., magnificently. The genitive would be a genitive of specification.
2 tn The construction uses the Hiphil participle again (as in the previous line) followed by the infinitive construct of הָלַךְ (halakh). This forms a verbal hendiadys, the infinitive becoming the main verb and the participle before it the adverb.