Android purchasing help!

1

ok... I'll admit... I'm a tech guy.. that needs some HELP!
I'm on T-Mobile... So that's the first part. I'd prefer from them as the wifi calling isn't like iPhones where I can buy any iPhone and wifi calling just works...

Requirements:
Android pay compatible
NFC
5 GHZ wifi (preferably AC, but I Could deal with N)
expandable memory
cardboard compatible (Part of why I want to test it out-- This thing: https://riftcat.com/vridge)
Hopefully cheap...

Someone please explain the following:
Google hangouts... does that do wifi calling, that would negate the need to have it from T-Mobile, however the financing at T-Mobile is great...
a podcast app that you can recommend that will download to SD card and resume playing when stopping abruptly. (This is one of the main reasons I'm looking into this... actually I could probably get away without android pay, just want to test out android decently not pick up the $20 android and say it's crap as the hardware is... crap)
Anything I'm missing?

I'm currently on a Windows Mobile phone, until my replacement iPhone comes in... then another one when they release the new one... This iPhone has a home after me... It's going to be weird going from an iPhone 6+ to an iPhone SE.