1- yes absolute right , pay khums from 1200.
2- means any expense which is over the average of the expenditure of your income group.
3-if it is necessary and not any intention to avoid the khums then yes it is consider as expense and khums will not applied
4- Only make sure this entertainment is not haram if it is then refrain from it
Expense for beautifying is halal but remember that be moderate in it.