Unlocked Verizon Galaxy S6 to T-Mobile

[AC Question]

I was given an unlocked Verizon Samsung Galaxy S6 that I now have on Tmobile. Most everything works with a few exceptions. I have discovered that if I try to update software it tries to access it from Verizon, obviously this does not work. How do I update the software? Secondly, the blue tooth functions dont all seem to work in my car. I have a 2012 Cadi SRX and with my old Windows phone it would read my text messages to me and let me dictate a reply. I cant find this function anywhere on my S6, also with my old phone I could stream music from my phone to the car, such as Pandora or some other sites. No such luck with my S6. Does anybody know how to fix this?