Is it proper to wear the white clothes which are similar in the ' Empresses in the palace chinese drama ' and wear white flowers as your hair accessories to attend your Chinese Friend’s wedding？why？

No it could be considered offensive to their culture

it can be both; depending on the situation at hand.

explanation:

let's just say i get in to a confrontation with someone, and they say "ur mom", it could be seen as an insult. or depending on the relationship or comfortability with the person it may be seen as a joke. the distinct line is how the chemistry behind the confrontation.