1. Vermins can be found in the western side of Xakuang skyway (north of Senji's corner)
2. The new AI update makes vermin scatter so farming is ridiculously slow.
3. No you probably can't farm them with a monk unless you find a way to survive through knockdowns and 10 degen.
But you know what they say: if old and prestigious professor says something can be done he is probably right. If he however says something can't be done he's most likely wrong.