Yes, you can play 4K videos on iPhone 8.
Yes, iPhone 8 does have Dolby Digital & Noise Cancellation.
Though Apple never mentioned the battery capacity on their website, during our review of the device we found that iPhone 8 does have 1821 mAh Li-Ion battery.
We are extremely sorry to inform you that we do not ship the products outside India. Further, we also suggest you buy it from Singapore only so that you can get the warranty for the product. Only Apple iPhone X comes with the international warranty.
No longer the gold standard, the iPhone 8 is still all the phone you need.