Facebook SDK - Like button

I would like to add Like button to my Unity App. When user click on the button, I would like to add Like on the Facebook page. I have found FB Like https://developers.facebook.com/docs/ios/like-button, but this is ObjectiveC (similar code is for Android), so not very usefull in C#.

Then I have found this: https://developers.facebook.com/docs/unity/getting-started/canvas and https://developers.facebook.com/docs/games/unity/unity-tutorial. This looks better, but there is no info how to do "Like button"

My scond question goes to FB review process. Do I have to have one for simple Like, or not. In the first like, I have posted, there is info that you need to have reviewed your app. But in Unity tutorials, there is not a word about it. Plus, how can I post my app to review ? Is web-player version enough, or do I have to upload them every version for every device I will target my app ?

This may be silly questions, but I am new to Unity and FB integration.