Compesatory off's differ from company to company, I will suggest that you should check employee handbook i.e. what are the rules laid out there. What we practice in our organization is :
For grade 5 and 4 we consider it as overtime and they payment of wage of that day will be as overtime i.e. 1.5 times the normal. If the employees is in grade 3 and above he / she will be provided with compensatory leave. Which he is entitled to take within a month from the holiday on which he / she worked. No employee can take CL / SL in advance as funda of leave is that you have to earn it. According to leave law of India every employee is entitled on 1 leave after every 20 days of work ( including sundays and gazetted holidays). It is the minimum criteria. So employee have to earn that leave and can't take it in advance. Also you can't give them advance leaves because accounts people wont allow it so. And your last query, only one day leave will be considered i.e. of tuesday as per your example. But if he is on last working day i.e. sat or fri whatever it may be then sunday and monday will also be considered as leave and will be deducted from his/her leave balance.
Hope i am able to solve your quires.
20th November 2010 From India , New Delhi