JOEL- It appears you have done a lot of study on this subject, and I can understand your confusion. I am confused a little myself about it, but for some reason I just don't let it bother me that much. My testimony in the Gospel is strong enough to give me faith to know that I will eventually have all my questions answered either in this life or the next. But of course that still doesn't stop me from studying it and looking for answers.
Many people have addressed this subject at all levels of Church authority and have proposed a number of explanations. Unfortunately we can't ask Brigham Young himself what he was thinking when he talked about this. We know that he mentioned the Adam-God topic several times in various speeches. The problem is that most of his remarks were not comprehensive addresses on the subject. He would mention only certain aspects of the doctrine and never really put it all together in a written form that everyone could study. Some understood and agreed with what he said. By the way, it was Orson Pratt who was unwilling to accept it.
I believe President Young knew about a lot of things on a such higher level of understanding than anyone else, that when he tried to explain it to others, his message fell upon ears that could not comprehend the concepts. I don't believe that Brigham Young was a false prophet. I do believe that he was trying to communicate some concepts, which people either inaccurately or incompletely recorded or that he was just plain wrong about. Prophets are human and can be wrong about some things. However, they still should not be accused of "leading the members astray", as long as what they are saying does not jeopardize our chance for exhaltation. Knowing if Adam is or isn't God the Father would be interesting, but it is not necessary for our life here on earth nor for our eternal salvation.
What makes President Young's statements confusing is that within the same speech and in other discourses, President Young definitely states that "Adam is Michael, the Archangel, the Ancient of Days;" which means that Adam is not Elohim, or God the Father.
President Young also explained that Adam helped to make the earth. If he only helped then that means that he was subordinate to someone who was superior. Young also states, "It is true that the earth was organized by three distinct characters, namely, Elohim, Jehovah, and Michael." Here he places Adam, or Michael, third in the list, and hence the least important of the three mentioned.
Here is something else Brigham Young said: "We are all the children of Adam and Eve, and they are the offspring of Him who dwells in the heavens, the Highest Intelligence that dwells anywhere that we have any knowledge of." Why would he say this if he thought that Adam was God the Father? He also said, "And what shall we say of our Heavenly Father? He is also a man in perfection, and the Father of the man Jesus Christ, and the Father of our spirits." Here he states that Heavenly Father, not Adam, is the father of the "man" Jesus.
Brigham once said that Jesus "was begotten in the flesh by the same character that was in the Garden of Eden, and who is our Father in Heaven." It sounds like he is talking about Adam, but Brigham knew that God walked and talked with Adam while in the Garden. So the "character" he is talking about could be God and not Adam. There are many other instances, like those I have mentioned, where Brigham Young correctly describes the proper identities and relationships of God and Adam.
I have heard people explain that Adam could be considered a god because of the divine role that he played in the pre-existence and creation of this earth. He possessed a celestial spirit and priesthood power and therefore was a God the same way that the pre-mortal Jesus was called a God. Adam is the mortal father of us all. When the end of the earth comes we will all have to answer to Father Adam, who in turn answers to Christ, who answers to God the Father. People say that this is what President Young meant when he said that Adam "is our Father and our God, and the only God with whom we have to do"
There have always been points of doctrine that are not fully understood by many, including prophets. God gives us light and knowledge a little at a time when He sees we are ready for it. When questions arise we have been told to look to the current prophet for our answers and then the scriptures, in that order. Both of them, however, must agree with each other.
One important thing to consider is that we don't have access to everything that was said on the subject. We are therefore confused because we can't see the whole picture as Brigham Young could. Recently there have been found five unpublished speeches of Brigham Young at the Church Archives in Salt Lake City, which further describes the Adam-God doctrine. A site called Doctrine of the Priesthood by The Collier's Publishing Company has some interesting information about these speeches. Check it out.
Until we find out more I'm afraid the answer to this question is going to have to be one of those "wait and see" things, to find out if Brigham was right or wrong. And what if he was wrong about this one single point of doctrine? What should we do about it? Leave the church? I don't think so. We should put our trust in the latter-day prophets who are here specifically for us today. God would not be a just God if we were not blessed for doing so. We should strive to strengthen our testimonies and have faith that we are going in the right direction and not worry so much about things that we don't quite understand right now. The Holy Ghost will help us to know right from wrong if we properly prepare our minds and or spirits before we ask for answers.