No. You cannot record 4k videos but you can play 4k videos on Honor 8.
Yes - absolutely. You are entitled to 90 days screen breakage warranty as well.
There are only 2 disadvantages of Honor 8?
01) No FM Radio
02) Single Sim
Yes, Honor 8 does have LTPS Scratch Resistant (Low Temperature PolySilicon) glass, which is even better than gorilla glass.