I think people are confused because Touch ID is what is being used to recognize a press in all these situations, even when it's unrelated to unlocking the phone and Touch ID technology. It's the metal Touch ID ring that's being used--not the fingerprint scan. They probably did it this way because otherwise pressing anywhere near the home button would be interpreted as a press or tap, as it's all one solid surface.
I don't think so. Otherwise putting a finger on the touchID sensor and then pressing with another finger *right next to it* should activate it. It doesn't. Even on the lightest sensitivity.
I bet the pressure sensor isn't electrically wired to the touchID functionality, which means they could just "fix" this with an option in settings... e.g. any pressure on the circle can register a click.