Hi HeartSong,
I will give this one my best shot.
First, I think we don't need these verses for they are not related to the "tree of life" and the "water of life". Rather they are speaking of geographical locations.
"And the Spirit of God moved upon the face of the waters." Gen 1:2b "And a river went out of Eden to water the garden;" Gen 10a
Now focusing in on your first question,
(Adam could eat of the tree of life in the Garden of Eden before the Fall?)
I believe that Adam and Eve both ate of that tree. Man was created to live forever and eating the fruit of that tree was how it worked. Death is not at all natural to humans. We find in Gen. 3:19 "...till thou return unto the ground; for out of it wast thou taken: for dust thou art, and unto dust shalt thou return."
Verse 22 would seem to contradict that they ate of the tree but I think it fits in perfect... "And the Lord God said, Behold, the man is become as one of Us, to know good and evil: and now lest he put forth his hand, and take also of the tree of life, and eat, and live forever." For man to sustain life everlasting in that created state he had to eat the fruit of the tree of life. But God did not allow us to live forever in a sinful fallen state. I cant even imagine the evils we would have done. Hence God threw them out of the garden. Gods judgement was what He knew was best for His creation.
Now all this was for our existence then. After we fell we changed. Our physical and spiritual being changed.
But Revelation 22:1-2 apply's to believers after we have our new resurrection bodies (1Cor.15:35-58). So we can partake of the tree.
As for the water, I'm reminded of Jesus' words to the woman at the well, "...I f thouknewest the gift of God, and who it is that saith thee, give me to drink; thou wouldest have asked of him, and he would have given thee living water." And again, "..."Whosoever drinketh of the water that I shall give him shall never thirst; but the water that I shall give him shall be in him a well of water springing up into everlasting life" (John 4:14). I believe that these two "waters" are closely related in that both give life.
Back in Rev.22:1 its interesting to me that both the tree of life and the waters of life are present together. There is probably much symbolism to these two things but I'm not familiar with it.
Hope that helps you, Doug