la gleki cu cusku di'e
Neither zanbi'o nor zangau are in the dictionary.
1. I wouldn't create any words that lack roots. If they lack then they are naljvajvo/cimjvo.
2. In other cases I would perceive suffixes as winning over prefixes i.e. like tanru work (expanding starts from the end).
Actually, that's kinda part of the problem. Like I've said, they've kinda become extremely common prefixes/suffixes like English "un-" or "-er", so adding every possible useful combination to the dictionary is a Herculean effort beyond what little people we have maintaining it in their spare time. {zabna} and {mabla} are especially bad this way, as their rafsi {zan} and {mal} has been combined with almost anything to mean "X in a favorable / disfavorable manner; X with a positive / negative connotation"