Praise be to Allah.
With regard to the first question, what the Muslim should do with regard to these events is to offer help to his brothers in Afghanistan and to make du’aa’ for them that Allaah will help and strengthen them, and support them.
With regard to the second question: if what you mean is that you are an employee who is required to work for a certain number of hours, such as seven hours a day for example, and you are able to complete in five hours the work that is expected of you in seven hours, then you leave and your immediate superior has given you permission, then it seems that there is nothing wrong with that, so long as the following conditions are met:
1 – Your staying there should not be essential to your work, such as meeting clients, rather it should be the case that the extra time is a waste of time.
2 – Your being fast should not be detrimental to the work you are doing, rather you should do it completely without any shortcomings.
3 – The department in which you work should not have rules against such behaviour (because most departments and companies make it a condition that employees be present during work hours).
If these conditions are met, then I hope that there is nothing wrong with that.