You pretend to ignore the other Ukrainians who live in the Eastern Ukraine and have different views from the ones of their current authorities. Yet some level of decentralisation as well as free use of Russian may quiet them effectively.
Probably, but decentralization now would only seen as capitulation by the Russians, and encourage them to push further aka secession.
There’s a reason why Putin says he would like a federal solution, and it’s one of the oldest tricks in the book: divide and conquer.