1. As indicated, you need to call or go into a Verizon corporate store in order to cancel a line a service. You cannot do it online. This is for your protection.
2. When you call or go to a store, you will be be able to get this information which will be dependent upon what plan you are on.
3. Verizon removed the email for Customer Service a while ago. It's gone and is not currently an option.
4. You can change plans online. Just log into your MyVerizon account.
5. They are not asking you to follow them on Twitter or Facebook. They are asking you to follow them here on the forums. That's the way that you can send Private Direct Messages to that person.