I have the Note 2. A friend upgraded his note 4 to Apple and will sell me his Note 4. He uses T-Mobile, will I be able to use it on Verizon without any problems?
Nope. The Note 4 from T-Mobile lacks the CDMA radio needed to work on Verizon. T-Mobile uses GSM not CDMA. Also it doesn't support band 13 for LTE.