If I port a number from Phone A to Phone B, will Phone A still be active? i.e. if a text is received on that number, will both Phones get it? If a call is made to that number, will both phones ring? Etc.
Nope, you don't port the number from the phone as such its the sim card. One sim will be 'upgraded' to the number you want while the other will not be registered anymore.