Yes, but in a true self defense situation, how do you recognize what kind of attack it is in time to put up the correct defense? How do you read your opponent? A big part of that read is his internal structural changes. The minute postural and positional changes that tell you push, punch, or heel palm strike. Reading those tells early is the first step to making those other planar intersections work for you.
1. That is what the conditioned response is for, to recognize the attack by web of knowledge and the plane it is executed on. This is the importance of repetition, a thousand times slow for one time fast.
2. Not really. Internal structural changes don't tell you anything, they are usually for aiding in gravitational marriage or straitening your spine so limb movement becomes easier or finally it could be pushing the hips forward and tucking thus creating a natural but learned armor to guard your organs from impact.
3. There are many stages of reading someone. The first is the conditioned response to an attack. It is why we drill SD techniques. When teaching a technique or form planes are taught from the beginning so students are able to use them just the same as they would use gravitational marriage.
Here is an animation for you to consider in plane theory the universal pattern and the universal sphere that I mentioned earlier.
Hope you enjoy it.
Have a nice day