Leave entitlements in India derive from state Shops and Establishments legislation and, for factories, the Factories Act. They differ by state and by establishment type.
Your policy sets what you offer above that floor. Establish the floor for each state you operate in first — with advice — because a policy below it is unenforceable regardless of what anyone signed.
Carry-forward: how much unused leave rolls over, and whether it expires. Encashment: whether unused leave is paid, at what rate, and when.
And notice: how far ahead leave must be requested, and who can refuse it. Every one of these is a dispute waiting to happen if it is not written down, and each is trivial to settle in advance.
It depends on state and establishment type. Establish it with advice for each state you operate in.
That depends on the leave type and the applicable law. It is not a purely policy choice.
Yes. They accrue and settle differently, and merging them produces errors at exit.
Half an hour with your own data usually saves reading three of these. The guides will still be here afterwards.