1. There are privacy settings- one will show everything to anyone , the other will only show your information to people you have friended
2. They may notice that you are not on their list of friends anymore, but they don't get a notice. I don't know this for sure- I don't think I have been unfriended by anyone.
3.This will depend on their privacy settings-see #1
Absolutely turn your privacy settings on to where you feel comfortable. There is a private message that can be sent that will only be seen by that person, it will not show anywhere on their page for anyone regardless of their settings.
When you do like or comment on something, it can be seen by all of that persons friends, and if one of those friends also comments it can be seen by all of that persons friends too. So it can get around quick.
I would suggest you start a yellowhammer page. You can give out tons of info that way. Come on you are not that old.