RE: times
Make the answer cell (eg. C1) to be date/time 1 - date/time 2
eg. =B1-A1
Select C1
Go to Format -> Cells
Select Number tab and choose "custom" in category.
Enter the text "[h]:mm:ss;@" in type text box.
It should show you how many hours have passed.
I hope this answers your question?
Regards, Rich