More than likely when you get your iPhone it will be assigned a new mobile # but all you need to do is call Customer Service to be transferred to the Porting Center for assistance. They will take the necessary information to transfer your Verizon phone # to replace the newly activated phone #. There will be no penalties and the process is usually completed in a few minutes.
As to your second question, once At&t ports your Verizon mobile # over, make sure that you call Verizon to change her plan to an individual plan, don't just assume it will automatically. Her Verizon contract will not be affected.
I wasn't sure where to turn with these questions but I recently bought an iphone directly from Apple and chose my plan, credit check, porting my number from Verizon and bought my phone. My first question is when I receive my phone and begin activation will Itunes know I already chose a plan and go through the process of porting my number from Verizon? The reason why I'm confused is most videos I've seen have you do that information after you get your phone, not before. My second question is to check with anyone who has ported a number from a family share plan from Verizon where your number was the additional line and not the primary number on the account. I put the information in for the account and my number. I talked to Verizon and they said it wouldn't affect the primary who is staying with Verizon, she would just need to change to an individual plan but sometimes wireless carriers do strange things!! I apologize if these are strange questions but I've never had a plan of my own till now. Thanks for any info!!