Q: Two iPhones, will it have the same contents

If you gave away or sold your phone to your friend, you should have followed the steps in here prior to letting the device go. If you did, you have no worries.

What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support

If you left your old iPhone signed into iCloud with your account, potentially, yes.

See this document: What to do before selling or giving away your iPhone, iPad, or iPod touch - Apple Support

IF you se the same Apple id you get will get the same imessages, your devices will both ring for facetime and you will share call history other then that they will not be the same

And if you didn't follow the above procedure and at least log out of iCloud, you will most likely cause ENORMOUS problems for you & your friend somewhere down the road (like when your friend tries to update the iOS).

Note that the WhatsApp and Yahoo apps will have their own unique logins.

If you left those signed in before you gave him your phone, he may very well have access to the data from those apps.

As with your Apple ID, if you have concerns, change your passwords ASAP.

Your Apple ID, used for iCloud, is completely independent of any non-Apple apps, like Facebook, WhatsApp and so on.

You should really change the passwords for any apps you don't want her to have access to.

Again, the Apple ID only covers thing like FaceTime, Messages, iCloud, iTunes Store and the Apple ID itself.

I don't know if Facebook would kick someone out in real time if you changed the password. Some apps do. If you change an Apple ID password, anywhere it is signed in will get signed out in real time.

Changing your password on your phone would most certainly not update the password on another phone. At worst, the other phone would just stay logged in.