I NEED SOME ANSWERS TO THIS QUESTION?

IF "FATHER", "SON" & "HOLY GHOST" ARE ONE

With all the explanation Muslims have been given to Christians about the misunderstood statement of Jesus saying "I and my Father are One" which means Oneness in Purpose but they Denied and Proceeded with their Claims that Jesus is God himself. 

Let's see then if they can defend this challenges:

They; Christians say:

"The Father is God"

"The Son is God" and,

"The Holy Ghost is God"

"But they are not Three Gods but One God"

And regarding the birth of the son, they say Mary was Impregnated by the Holy Ghost.
Again, they say that the Father Incarnated and came down as Jesus through Mary.
Now, if all these three are on board, the questions goes as follows:

1. Was Mary impregnated by the Son (Jesus) even before she gave birth to the same son?

2. Was Mary impregnated by the Holy-Ghost and incarnated the Father into the Son?

3. Who created Mary?

4. Ask any question regarding this for them to answer..... .......