1) You apparently have not been treated with any drugs that are reliably effective against M. genitalium, e.g.
moxifloxacin (trade name Avelox in the US). You might mention it to the GUM clinic. However, as implied by my opening comments, I'm not sure it matters.
2) I agree there is no known danger to your partner, either by vaginal, anal, or oral sex.
3) There is overlap between NGU and prostatis, both in symptoms and in diagnosis.