Go to iCloud.com in a web browser on a PC and create a new account. Then on his iPhone sign out of your account. Then sign in to his iCloud account. You can choose which iCloud components he wants to use (email, calendar, contacts, etc). I suggest leaving them all on even if he doesn't use them at first. This will give him an email address as well--
name@icloud.com.
If you want him to have access to any apps, music, video that you've purchased, then in Settings, ITunes & AppStore, make sure you are signed into your account. This does mean though that he would need you to enter your password for any purchases he might make.
Then in Settings, Messages and Settings, FaceTime sign out of your account and into his new iCloud account.
As far as a shared calendar, on your device create a new calendar and you should see an option to share it with someone. Enter his iCloud email address. He will get an email on his phone that he can then go to his calendar and accept the invite. Then you will have a calendar that you can both see and add event to. You can also share lists in the Reminders app in a similar way.