calculate the working days and Holidays

please provide formula for solving these question:

1. Find the working days between 15th Nov ’09 to 28th
2. Add a column that shows the date after a number of months from today’s date. The number of months from today’s date for each of the country is mentioned in column “No. of Months after which revised”.
3. Find the date our training will end using excel considering the fact that SAT and SUN are holidays. (Use the date when your training started)