First Question - Dangers of publish personal information on social networks

I use websites like instagram and facebook, both networks ask you for email and phone number, however when it comes to accepting friend requests I am very careful, I only accept people I know and there is also the option to make the account private, which allows you to receive notifications when someone sends you a friend request. 

When someone accepts strangers you run the risk of them being a thief, a stalker, etc. Also when you accept the friend request the stranger can access your personal information, know your address, steal your information and use it for their benefit or extort you through messages, you should not take it lightly, you can enjoy social networks as long as you understand that your personal information is not for everyone.