I would quarantine the snail first. If all is good then acclimate the snail to it's new tank. When handling them you gently grab the shell and try to slide them up the wall of whatever they are in. Just make sure you are gentle with them. Then I normally set them on the gravel and then wait a min or two. Then the snail will pop out and start cleaning. :D Nerites are hard to get off the side of the walls of tanks, lol! Very strong little guys or gals. As for the tank nitrites my tank is not cycled so a more experienced gal or guy will have to help you with that. As for boys or girls *shrugs* I have no idea. Sorry. I will google it for ya. ;)
My Bettas: The Great Bambino *Babe* my big boy Marbled PK, Rosie my dainty Crown Tail gal ,my little HMPK guy Ginger Baker, Slash my Reptile HM male and my HMPK sweetie Sterling.