You only get sent a cheque if you live in the US - anywhere else requires PayPal, and India is exempt from receiving cash for points.
You choose. Whenever you want, go to your page and click on "My Points". It explains how to cash them out on the bottom of that page.
once you put in your mailing address, and after they send you the check, do you have to put it in again to receive another check?
What happens if you cash them in ?
You get sent a check.
Oh awesome :P