To stand in Persepolis in modern Iran and look out, as Darius the first must have done…

‘To stand in Persepolis in modern Iran and look out, as Darius the first must have done, at the immense sweep of fields and mountains is to grasp the vastness of the ancient Persian Empire.’

The sentence contains no errors; however, I am slightly confused. Isn’t the word ‘done’redundant? How do I know if a word is redundant or not? Thanks!

[If there were] a power failure, the hospital will run on electricity from its own generators…

Hello. Hope you are doing well. Could you please explain the following questions?

‘[If there were] a power failure, the hospital will run on electricity from its own generators, which can operate for 200 hours.’

[If there were] is incorrect and should be replaced by [Should there be]. Can you please explain why?

Like her husband, Jackson Pollock, Lee Krasner was an Abstract Expressionist artist, and [the two of them both] influenced each other’s work.

‘Like her husband, Jackson Pollock, Lee Krasner was an Abstract Expressionist artist, and [the two of them both] influenced each other’s work.’ [the two of them both] is incorrect and should be replaced by [she and Pollock]. Is this simply a case of wordiness or is there something else going on? Thanks!