There is no liking system in Gmail service. Facebook Like websites have a system of liking. Gmail just deals in sending and receiving mails.
You cannot guess any Gmail address. The addresses of gmail belong to the owner. They are like the lock on the account.
The address book is like a contract book in gmail. It can be used to store contacts in gmail. It is above the compose mail where Gmail is written and is a drop down.
an email address that is not your main one, but a back up. like Gmail.
You have to delete all others manually. They cannot be deleted automatically by Gmail. Then you need to create the new Gmail address.
No, you can't find anyone's email address from Gmail. It is not like social networking websites. You cannot peek into other's profiles.
You can change your Gmail address after you change your IP. You however do not need to do that. It is because gmail is independent of IP address.
You can use filter in Gmail: [http://support.google.com/mail/bin/answer.py?hl=en&answer=6579]
Depends what email it is, like yahoo you can but not on gmail or aim
You can transfer your email address to your Gmail address book. Gmail can import various contacts from others. This can be done in the settings and then import.
You cannot get the gmail address of anyone by their name. The gmail addresses are unique for everyone. The serve the purpose of logging into the account.
You can go back if you opened Gmail earlier. You can type in the URL in the address bar. You can also type in the IP address for the Gmail.
an email address that is not your main one, but a back up. like Gmail.