Salary Calculations - If Enrolment by company to deduct PF optional or mandatory?

Dear all, My company is having 17 employees and is growing. We would soon be 20+
I need to know following.

1. If Enrolment by company to deduct PF optional or mandatory?
2. Is ESIC optional or mandatory?
3. Is it optional or mandatory to deduct Gratuity

Can Someone please answer these and Also If anyone of you can send me latest Salary calculator. My company is in Gurgaon.

Thanks in advance.
Jagjit

Organizations with 20 or more employees are required by law to register for the EPF scheme, while those with fewer than 20 employees can also register voluntarily. The salary limit as of now is Rs. 15,000/- or less.
The ESI scheme is applicable to all factories and other establishments as defined in the Act with 10 or more persons employed in such establishments and the beneficiaries' monthly wage does not exceed Rs 21,000 are covered under the scheme.
So EPF Scheme is presently inapplicale but ESI is applicable if you are in a covered area. If so, start with ESI coverage, and when the employee strength touches 20 start PF coverage. There is no need to rush to EPF coverage as voluntary coverage will take time to process and since you are going to add more numbers shortly, a practical approach would be to wait for the coverage.