the person who has signed on behalf of the dead person
You write it as the "late" Mr./Mrs. XYZ
No. The only persons who can declare a person dead are those who write death certificates; a medical practitioner or, in the absence of a body, a coroner.
biography
No. If the person is dead how can he write on YouTube. I too was freaked out until I noticed there are no such things ghosts and how can they write letters on YouTube.
They are usually pronounced dead by a Doctor or health professional. On a death certificate they generally write the time of death and the cause. So they need to make an official declaration that the person is actually dead and note the time.
None. If a person is dead they have no life because they are dead.
You can write them all you want, but who knows if they read them.
No. A dead person cannot communicate with a living person at all.
I know it is weird but yes.. You can get married to a dead person!
Eulogies are usually delivered by a family member or a close family friend in the case of a dead person. You must know certain things the person did in his lifetime.
for a paralysed person, no need of artificial breathing. And for a dead person that is not possible.