Some of 'em can but it's not a prerequisite. I'm a transcriptionist and I deal with them spelling words they think I might not know quite incorrectly.
Not necessarily. One of the smartest people I ever knew couldn't spell at all. Every time he wrote a tricky word, he spelled it differently.
I advise everyone here to stop worrying about spelling, and think about the serious matter of Rush’s health.
BTW: Doctors have some of the worst handwriting, and bad spelling may simply reflect the fact they have more on their minds than typing.
I gotta give you five stars for that one!