A:AnswerAs a person with big ears that fit in the over the ear headphone cups, i would suggest it’s safe to say they would comfortably fit with behind the ear hearing aids.
A:AnswerWhen I first got mine, they would disconnect all the time, I let them die & then made sure they weren’t connected to another device including phone, tablet, anything really fighting for the connectivity and they work brand new
A:AnswerI'm not sure about specific headphones, but extreme cold temperatures can sometimes affect electronic devices. It's always a good idea to check the manufacturer's guidelines