Will my Verizon (CDMA) iPhone 6 work in GSM-only countries?
Does CDMA work with GSM towers?
Verizon is factory unlocked for GSM carriers. You should be able to use it with a GSM SIM outside the States.
It will if the phone is network unlocked.
Better check up with Verizon and get them to network unlock it for you.
Question 1 ) Yes. it will work. also you can check whether your iPhone 6 is carrier unlocked or not, contact Verizon and verify before roaming.
Question 2) Different technologies, BTS/Node B depends on the network operator. :-)