Just go to "log in", sign in with your mobile number and you can change any of your details.
Click on the "forgot password" option in the log in page and follow instructions to change your password.
Just log in to your account and and edit any of your personal information.
Yes. Just log in to your account, go to the "Profile" page and edit your address and other personal information.
You can use any credit/ debit card issued by an Indian bank.