All above forms of your mail id are valid and points to a single account. Have a look at the screenshot.
Also, gmail allows you to create more alias of your id by using "+" sing in your mail id. So if you want to subscribe to some mailing list or some group then just use, "firstname.lastname@example.org"
e.g. 'email@example.com' or 'firstname.lastname@example.org'
So you can distribute these alias among your contacts, then apply filters according to the destination id and archive them into separate folders.
Let me know if any more such variations exists.