A:AnswerYes. If your guitar auxiliary cord is small like on a smart phone opening, then that is exactly what you want to do. One side is 1/4" Male and the other is small female.
A:AnswerShould work. It's just an adapter. Worst case scenario, you return for a refund. But I'm confident if the smaller fits into the back of the bigger, it's going to work
A:AnswerYes it will. That's why I purchased this item; to connect my headphones to my Adagio Keyboard. I have the larger holes on the front of my keyboard. This adapter let me connect my headphones to my "piano" keyboard.