The other qualities of God described in the quran contradict certain concepts you have stated. When it is said in the quran that God has created the "heavens and the earth", water is part and parcel. Additionally the reference extends to beyond water alone, IIRC this term tends to refer to the universe as a whole.
One has to also relate these conceptual definitions of the creator to what is around us in reality, it does not suffice to ramble on philosophically when you could be weaving yourself an intricate web of lies for no just ends.
You have to understand one thing, space and time are fundamentally interconnected via the fact that the speed of light is what mediates every interaction between anything. There is no such thing as time in reality in the manner in which we percieve it and Allah in the quran knew this very well (32:5); the reality is that space/time is a shape (manifold) containing "events" and all events are relative to each other but they can be placed in order. If you believe first and last means "first point in time" and "last point in time" then you will have to come to the conclusion that "Allah" might not be eternal. However from a realistic perspective this could only mean the first and last events which is a very different story in which there is indeed much room for eternity.
This certainly raises the question of God being "eternal". How long is "eternity"? I believe that Allah is REAL. Everything in reality is formed on the basis of cause and effect. Therefore, if Allah is REAL, then He had to come from somewhere; there's no such thing as something or someone "always being here/there" - that concept doesn't exist in reality. So, where did God come from? What caused Him, and how long has He been present?
There are too many factors in the Qur'aan to overlook when it comes to Allah's "realness". For example, the scripture said that He says "Be," and things come into existence. Well, how can God "SPEAK", or say anything, if He doesn't exist in reality? It says that He talked to Iblis. So, who is Iblis, and where did he come from? In order for him to speak to God, he and God must both be real people. The word used in the ancient Hebrew and Aramaic writings concerning the reality of God (Allah) was "ruach", which meant spirit/breath. This force couldn't exist without a physical body to inhabit, and the Qur'aan says that Allah blew this "ruach" into Adam. So, who is Adam?
And, finally, when the scriptures, at least the ancient ones, referred to "the waters", it wasn't talking about the composition of the Earthly waters like seas, lakes, and oceans. It was referring to primordial waters, which, theoretically, consume the total measure of the Universe. They don't necessarily refer to literal "waters" as we know them; they simply refer to the abundant energy forces within the bounds of Nature, being the infinite "source" of everything, including God Himself. The Qur'aan promotes an idea similar to this as well, saying that Allah created every (living) thing from "water". Well, what water was it referring to? The Atlantic and/or Pacific Ocean? The Nile River? The Dead Sea? WHAT WATER?
Where did this "water" come from? The Qur'aan doesn't say. In fact, based on it's explicit doctrine of Allah shaping the heavens and the Earth, one would think that the "waters" were already present, since the book never mentioned Allah creating or establishing them. NOT EVEN ONCE. The first act concerning these "waters" was Allah placing His throne on them... Do you think this is coincidental?
I guess the most significant question on this issue is: Do you believe that Allah is "real", or is He "unreal"? People make the claim that God is a reality, yet they say that He can't be seen, heard, smelt, touched, tasted, or even imagined! So, how do you know that He exists? The answer is: He CAN be seen, heard, smelt, touched, and (if that's your thing) tasted. He exists in reality. That's the only way that it makes sense for Him to 'show Himself to a mountain' - He has to be in one place at one time, not incorporeal. He must be real Person. Basing the concept of God as being incorporeal provokes the assumption that He is the Universe itself, all-encompassing and infinite. Do you believe that to be the case?