My concerns on Facebook

...and other social networking media.

Is this really required? If so,
1. How secure is my personal information?
2. How much should I reveal and how much should I keep to myself and my close friends?
3. Facebook's privacy settings are shoddy. (read this).
3.1. Facebook is a business.
4. Are there better alternatives?

I am still researching. Any update will be reflected in this post as edits.

Regards,
Sauvik.