Swiggy hdfc card help

My brother has received this card recently, and i have couple of queries 

Is there any monthly limit on the cashbacks?

Can i use it in multiple swiggy accounts and earn cashback ?

If i use it on Samsung / Flipkart to purchase something on emi and then cancel, will i get 5% cashback ? (i have heard hdfc has stopped giving rewards on transactions when there's instant discount )

Kindly help with these queries 

Thanks in advance