4) Why did crosses and other symbols of Christianity have to be hidden before the edict of Milan?

I believe because it was for the Christian persecution that took place around A.D. 64, since a lot of Christians did not want to give up their faith, but did not want to be killed, they hid every Christian symbol (I guess this could be the right answer, hope I could help!)

b i think if not it should be a pretty sure but not