You don’t need to provide all the personal information to the app for logging in.
Make sure to click the option labeled “Edit the info you provide” when logging in. When you click this, you see exactly what you’re sharing, and you can make changes before proceeding. For example, you could choose to share your email address and Likes with the app, but not your friend list or your birthday.
No. Facebook Login does not allow apps post to Facebook without your permission. You have the choice of whether or not you allow an app to post to Facebook on your behalf – you’ll be asked for this permission specifically. If you don’t approve, the app will never share anything to Facebook for you. And if you do approve, you can choose which audience sees your posts (Public, Friends, Only Me, or a tailored list like “Close Friends” or “Family”).
You may not have checked which apps are connected to your Facebook account in a while — You might not even remember which apps you’ve used. It’s time to clean things up! Visit your App Settings to see a list of the apps you use; it’s a clear and easy way to keep track of your Facebook-connected apps. You can easily manage your apps and even entirely remove apps that you don’t use anymore.