Isiah53:
I don't believe that having a body is a requirement for being a god. The Holy Ghost is a member of the godhead though I don't know if he is really considered a god.
It is a good question though. Slightly off topic but I use to read the story of Ammon and King Lamoni and think it interesting that Ammon so readily confirmed Lamoni's Great Spirit belief. This makes more sense now. Jesus Christ, the God of this world, was a spirit at the time. I had never thought of that before.
We know Jesus was the only perfect person to live on the Earth. He probably had thoroughly proven himself in the pre-existence. Remember, too, that the time line as we know it is not the same as eternity and that God's time is one eternal round. Thus, to say he was a god before getting a body might just be linear thinking.
Really you have to understand a couple of other doctrines. Mostly reading Section 93 teaches us how Jesus Christ became God.
I look at it more like Jesus's Calling (Same with the Holy Ghost). Like in the church today when I get a calling I get the power given to me for that calling. (I am set a part for it). The same holds true for Jesus Christ. Because he qualified for that calling, he was called to be part of the Godhead.
Jesus Christ didn't have any power of himself, his power came from his Father in Heaven. The power to Create worlds, wasn't Christ's power, it was God's power given to Christ for that purpose.
As Christ came to earth, any power he has was still because of what his Father gave him. This doctrine is called Divine investiture.
But as Christ passed through mortal life, he overcame the things of the flesh, grew closer to Heavenly Father. After Christ died and had passed through mortality, Christ had then become a God in his own Right. The power was then given to him, he now had his own power.
The same holds true for each of us! We pass through this life, qualify ourself for God's power.
When I came home from my mission, I went up to BYU. There I was told that I could take a Spanish test and I would be given 12 units of whatever grade I got on the exam. I took the exam and got an A, so they gave me 12 units of A in Spanish without ever having to attend a single class. I think that this is what Jesus did. He got an A on the pretest (I.e., the preexistence), as did all children who die before the age of accountability, and essentially his calling and election was made sure in the preexistence. Although He was not technically exalted at that time, nevertheless, that was a technicality. His exaltation was guaranteed, and all He lacked was a physical body. It was rather like someone who has their calling and election made sure in this life, except that Jesus and all children who die before the age of eight had their calling and election made sure in the preexistence.