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.
Yes, iPhone 8 is slight heavier than iPhone 7. Apple iPhone 7 is 138 Grams while iPhone 8 is 148 Grams.
No. iPhone 8 does not have the FM radio.
Yes, you can use the old AirPods with the new iPhone 8.
No longer the gold standard, the iPhone 8 is still all the phone you need.