Contacts don't update on my new iPhone 6

I must have missed something in the setup of my new iPhone, because my Contacts are not updating from iCloud. I tried signing out of iCloud on my iPhone and signing back in, but that only made it worse. Most of my contacts are gone from my phone.

Also, when I signed out and back into iCloud, my Apple Pay debit card was deactivated, according to an email from my bank. How do I reactivate it? I'm not familiar with Apple Pay... yet.

Related question: I got a text message on my iPhone that says "Your iCloud Keychain verification code is: xxxxxx" I have no idea what I was supposed to do with that.