Why do you need to know the gender of the partner? That it not important to know, nor does it matter. This just tells me you have preconceived notions about how they should act and want to formulate your response based on their gender. And if any of the post is confusing to you, you just have poor reading comprehension. :)
It’s as simple as swiping down on the screen. I agree it’s a little under-sensitive if you try to swipe down from the circle with the icon at the bottom. But you can swipe down from anywhere on the screen and it will decline the call.