Yes, according to what I experienced, they keep a track of email address too (you can always create a free email at any of your favorite email providers)
the whisper box is used when you want to PM (Forum language) someone. To use it, type the name of the user you want to send a message to (case-sensitive), and input your message. You should be receiving message later of course. To find out if you got a response, when you log in, you should be seeing the name of that user Last Active on the Whisper Box (that way you can find out if he/she responded to your inquiry).