VBA/Function for complex date difference

Hi,

Can anyone help me with a VBA or function to calculate the difference between 2 or many more dates all grouped in a cell?

Based on the attached workbook and how the data is structured(all the time) it would be useful for me to get the following data:

a) How many days(or hours) have passed since creation of the Case and the date of the first comment of the Handler (date of creation of the Case = all the times the first date from the bottom, the Creator's first comment date).
b) How many days(or hours) have passed between each subsequent comment of the Handler.
c) How many comments have been totally placed by the Handler for that case.

Finally, it would be excellent to not count weekend days and if time passed is less than 1 day - show the number of hours.

Appreciate your help