Trending @Cognizant; Need clarity on Leave encashment

My LWD is December 19th and I have 30 earned leaves. I have few questions on encashment.

1. Is there any cap for leave encashment like these many leave only come to encashment?

2. When I see the calculation it is coming on basic.but I have nps deducted by employer.will that also considered on basic?

3. As per my understanding leave going to laps on 31st December, is it correct?

Please answer if someone knows