You can redeem it into cash in 1:1 ratio. For promotional rewards, you don't have to wait for redemption. Whereas for 1% cashback, min points required is 250.
In NetBanking, Go to cards> Debit cards>Enquire>Cashback redemption>select your account> and there you have the screen for ooints redemption.
Yes, its 1st of every month.