First of all if your co. follow a 'leave policy' this policy should guide you on these issues. If no leave policy in vogue, my views are as follows:
1. does an employee gets leave in probation period or not.
= Yes, since Probation period service also part of regular service employees who are on probation irrespective of the duration would be entitled for leave credit for such period.
2. this leave of 2.25 if not availed gets carry forward to next month or not.
= Yes, unutilised leave at credit of any employee could be carried/brought forward for further periods, however upto a maximum of days prescribed under the relevant act applicable. Yours' must be pharmaceuticals, a manufacturing unit, I believe should be under the Factories Act. If yes, for further stipulations read the Factories Act to follow.
3. if an employee takes leave friday, saturday, sunday, monday and in that saturday was a festival holiday. now in this all 4 days is taken as leave or only 2 days friday and monday.
= Hope you are aware of the concept of 'prefixing' & 'suffixing'. Generally, holidays & duty off days either immediately 'prior' and/or immediately 'after' the leave days approved can be prefixed and suffixed. However those holidays & duty off days intervening, i.e., sandwiched inbetween leave days are counted as leave days only. But in case if the employee avails only CL of more than one day and holidays & weekly off days are sandwiched inbetween CL in such an event those days remain as holidays & weekly off days and not as leave days. Some employers' leave policy stipulates certain restrictions such as, i) more than one day CL is not permissible ii) CL cannot be combined with any other types of leave i.e., EL/PL/SL/ML.
4. one employee joined in our company in Jan. wants to take 10 days leave for marriage function, now what to do.
= Not eligible, atbest he just completed only one month service having joined in Jan.19, if yes he would be eligible only for 2.25 days not more. I believe your Co.may not encourage Leave Without Pay (LWP) during probation period.
7th February 2019 From India, Bangalore