The defense with the feet I got from someone who had to defend themselves multiple times. I don’t remember the details, but it’s about the easier way to keep distance from their mouth without it biting onto anything… idk. I’d say, check some youtube videos or other resources of people who talk from experience. :)

I think another important reason is to keep the face away. If you were to use your fists, you’d have to lean forward, bringing your face closer to their mouth. You’re also not allowing them to bite anywhere, like your legs. Of course, much like a knife fight, you don’t wanna be in this situation in the first place.

The palm thing, if you’re already doing a lot of other things right, it probably doesn’t matter much. But I find it signals more intent that you mean no harm. And by the time they come that close to you, I don’t see them attacking you, like ever. And if they were to show hostile behaviour beforehand, you have time to change your hand position and stand up.