"Which is not created until the fourth day and which could not sustain life on earth."
Did not say the Sun was formed. There was light already.
Go look what happened on the first day.
"A day is NOT defined by the Sun or the moon. A day is one rotation of the earth on its axis. It is most definately applicable."
Wrong.
The Earth would not necessarily rotate on its axis if there was no Sun to orbit. Indeed, it probably would do little more than drift along. It almost certainly would not have a 24 hour day without the influence of the moon.
I've often heard the term "in the day of", meaning a long period of time. Such as "in the day of Abraham".
Day is pretty meaningless in Genesis, particularly since Gen 2:4 starts all over from the beginning and tells a completely different story.
Bible litteralists claim that this merely retells the same story. But there are some subtle sequence differences between the two.
Bottom line. The Bible says God did it. Science attempts to tell us how He did it by examining Gods creation directly.
Since there can be no conflict between Gods creation and Gods Word, then someone has interpreted something wrong. Since Science has accumulated far, far, far more evidence in the matter than a few confusing words in the Bible, I believe their version of how God created the world is correct over your interpretation of Genesis.