A:Answer 1. Basket ground for the carafe.
2. Single serve pods in the adapter without the mesh use the capsule button.
3. Single serve ground in the mesh adapter use ground coffee button.
As for the tube, Different compounds are extracted from the coffee grounds after different amounts of time in water, so the first coffee that drips out is usually stronger than the last; the destratification tube ensures an even mix.
"Popular Mechanics" https://www.popularmechanics.com/technology/gadgets/a13150404/things-come-apart-coffeemaker-december-2017/