Regarding 1): rclone does the job. That's what I use with B2.
One of their employees pretty much said exactly that here on HN recently. I don't have the comment bookmarked or anything like that so I can't cite it for you, but I do remember reading it.
I'm paraphrasing, of course, but s/he basically said "the math doesn't work out" (for the regular service, not B2 (obviously)).