my ipad is stolen

To find it you must have setup Find My on the iPad before it was stolen, and registered it in iCloud's Find My Phone function. If so, login to iCloud, go to Find My Phone and see if the iPad shows up. If it is turned off, not connected to the internet, or has been wiped clean by the thief it will not show up.

Change all of your passwords associated with accounts on the iPad, notify your insurance company, and since it is cellular, notify the service provider incase they can blacklist it and deny it access.

Apple (and no one else) can not assist (with serial number or iCloud) in finding a lost or stolen iPad.

Report to police along with serial number. Change all your passwords.

These links may be helpful.

How to Track and Report Stolen iPad

http://www.ipadastic.com/tutorials/how-to-track-and-report-stolen-ipad

Reporting a lost or stolen Apple product

http://support.apple.com/kb/ht2526

iCloud: Locate your device on a map

http://support.apple.com/kb/PH2698

Report Stolen iPad Tips and iPad Theft Prevention

http://www.stolen-property.com/report-stolen-ipad.php

How to recover a lost or stolen iPad

http://ipadhelp.com/ipad-help/how-to-recover-a-lost-or-stolen-ipad/

iCloud: Locate your device on a map

http://support.apple.com/kb/PH2698

How to Find a Stolen iPad

http://www.ehow.com/how_7586429_stolen-ipad.html

Apple Product Lost or Stolen

http://sites.google.com/site/appleclubfhs/support/advice-and-articles/lost-or-st olen

Oops! iForgot My New iPad On the Plane; Now What?

http://online.wsj.com/article/SB10001424052702303459004577362194012634000.html

If you don't know your lost/stolen iPad's serial number, use the instructions below. The S/N is also on the iPad's box.

How to Find Your iPad Serial Number

http://www.ipadastic.com/tutorials/how-to-find-your-ipad-serial-number

iOS: How to find the serial number, IMEI, MEID, CDN, and ICCID number

http://support.apple.com/kb/HT4061

 Cheers, Tom 😉

I just received a notification that my stolen Ipad has performed a Facetime phonecall with my number and email address (notification sent to my cell phone!), even though the data plan has been disabled, is there any way to disable this from the theif or to now track this down even without me being able to find it in my iCloud?

Tracking it down without having Find My iPad turned on is going to be very difficult. But, to avoid the Facetime stuff, you should change your Apple ID and iCloud account passwords (if they're different accounts).

Everything Ralph Landry1 said is correct.