Learn English – How convert sentence with verb “cut” to passive

Number (2) is fine, correct and natural.

Number (3) should say, 'Some money was given to her.'

Number (5) is close, but the 'to' should be replaced with 'by him': 'She was given some money by him.' However, you could omit both so it's exactly the same as Number (2).

Number (6) is fine, correct and natural.

As for the best way to get this into the passive voice, I would say 'She was given some money by him' is your best option.

Without going into grammatical issues such as what "known" is, whether it is in the passive voice or not, whether it is a verb or an adjective, and such, and without caring about the risk of information loss or change due to the difference in information delivery, which is the whole point of the passive voice, you can rewrite the sentence with know like this:

The individual is rarely brought into the spotlight in a country that/which people/we know for its collective thought.

(You may also find this good answer on relative clauses and pied-piping useful.)