Receive FaceTime calls dialed to my iPhone number
You should be able to use your iPhone number for FaceTime on your Mac, but I have heard of cases where the phone number didn't get recognized at first.

Make sure that you have 10.8.2 installed. Then try toggling FaceTime off and on in your iPhone's settings. That re-registers it with Apple's servers, and should list the phone number as an option. If it still doesn't appear as an option on your Mac, turn off FaceTime on the Mac (not quitting, actually disabling it from the menu), then sign back in to it.