No. Vivo NEX does not have the FM radio.
Yes, You can play 4K videos on Vivo NEX.
Yes, Vivo NEX does have the fast charging support. It takes only about 30 minutes to charge up to 50% of the battery.
No. Vivo NEX comes with 128GB internal storage and it does have the OTG support as well. Vivo NEX does not have the memory card slot.
The Vivo Nex S is a unique smartphone. It looks great, it’s built beautifully, has the best processor you can currently find in a phone and a huge, truly edge-to-edge display.
The Vivo Nex brings some truly cutting-edge technology to the table but does so with an all-too-common mix of familiar failings. Even though we don't think it's the phone you (or we) really wanted it to be, it's still one of the most exciting phones we've seen in a long time.