1- Generate a calendar in Excel
Here is how to generate a calendar in Excel. Using Excel 2010 in my case.
In cell B1 (by example), put a date :
In cell B2 :
Then you just have to drag-n-drop down and right (or left).
To highlight saturdays and sundays :
Here is the result :
2- Number of days in one month
Put a date in cell B1. Then in another cell, formula is :
It will return the number of days of the month in cell B1.