A:Answer Unlock can be done, only after you pay off the phone.
So, if you lease the phone, you'll need to pay monthly for 18month then get it owned by 'Buying at the end of the lease price'.
Or you finish 24Mo installment Or pay full price outright.
Then, unlock can be requested to carrier for unlocking, then can be used with any carriers. Including Verizon, not to mention any other GSM based services.
Phone doesn't come unlocked from the beginning.