why is it (nic o niej nie wiesz) but then (wiem o niej dużo)? is there a rule to place wiem or wiesz before or after ?
"Nie wiesz o niej nic" seems okay to me as well, but somehow "Nic o niej nie wiesz" seems... stronger.
And you can also say "Dużo o niej wiem", with pretty much the same meaning.
Why nią or niej?
'nią' is wrong here.
'niej' is just the Locative form of 'ona'.
I know lots about her
why not 'I know her a lot'
That sounds unusual to me.
would "I know her well" be a good translation as well? seems like a more natural thing to say in english
I'm afraid I have to disagree. You can know a lot about your great-great-grandmother, because you've heard a lot of stories about her. But that doesn't mean that you know her well.
Are "dużo" and "bardzo" interchange in situations like this one?
No, I don't think they're ever interchangeable. "dużo" means "a lot", "much" and "many", while "bardzo" means "very".
Good to know. Thank you