How is the “o” used in this Czech sentence? And can it be omitted and still be correct?
It must be there, it is a comparison. "o hodně"="by much","by a lot".
How would you say "He was married to a much younger woman"?
"Byl ženatý s mnohem mladší ženou". That's grammatically correct but kind of improbable sentence in Czech. Following formulation of the same fact seems better to me: "Měl mnohem mladší manželku."
Can we use "Vzal si mnohem mladší ženu" instead? Will be there any difference in meaning in that case?