How to use Wi-Fi to save iphone data usage?

Once I login to my home Wi-Fi, will the iphone 5 remember the password and stuff and I never have to log in again as long as in settings, I say "Wi-Fi on." Also, does this conserve data usage?

As soon as it is setup, your phone will auto connect to Wi-Fi whenever you're in range, as long as you have Wi-Fi on

And yes it conserves data

Yes your phone will save your password if you save it in your phone while submitting your Wi-Fi information. Also, it does save you on your data package. You can also log into other people Wi-Fi and it'll save your data too.

Yes it will remember your password and it depends on your network and price plane whether or not Wi-Fi is included as free or if it comes off your dater allowance best thing to do is ring your network provider and check, if its free great if not just put your phone on to airplane mode then turn your Wi-Fi back on while your use the Internet at home you want get phone calls but you won't get charged for using the Internet ether as your network will be turned off hope this helps