Didn't know Crimea was majority Russian.
Again, murky. The Russians put Russians there over a long period of time to displace the ethnic Tatars so they could eventually win a referendum. Long term planning, and they've been trying to do the same in Donetsk. I really don't know if they've got enough there to win a referendum, I doubt it otherwise it likely would have already happened. Maybe pulling the war trigger was premature, should have waited until the Russians did have a majority in the Eastern regions.

Arguing somewhere is "historically Ukraine" is kinda ridiculous though. Ukraine didn't exist as a sovereign state until 1990.