amn't is an acceptable abbreviation in Ireland.
Bíonn mo bhean chéile ag magadh fúm mar sin, agus í as éirinn thuas
amn't is acceptable in English
source: Oxford Dictionary
Do verbal nouns have gender?
Oh, goodness. I'll have to go back into my notes and color-code them all appropriately now. Go raibh maith agat arís!
Why? How often do you need to express the gender of a Verbal noun?
I'm not saying it never happens, but you probably have better things to be doing with your time.