Katerinah,
Allow me to take a stab at some of the other questions you pose. First, God is a pure spirit. He therefore has no gender, and although we use the term 'He' to refer to God, it is because scripture has revealed God using masculine language. So God is a spiritual being and as revealed by scripture, that is three Persons in one Being. We can know via reason alone that God exists but this latter point about the Trinity we can know only by God revealing it about Himself. One could say then, that God is a community of persons, and from all eternity each person loved the other, and therefore God has no needs. We can also say God is love. God is self-sufficient and when he created He did so out of love, not necessity.
Now you need to realize God is not human. Nor is God a corporeal being. God has no physical body since He is a pure spirit. This leaves us with the question of how, if there are corporeal beings like us, and they must in some way come from God, then how can this be so if God is simply a spiritual being? The answer lies in realizing God has knowledge of everything that can possibly exist apart from Himself. In God's mind is the possibility of everything that can exist. This is what we mean when we say God is all-knowing. Yet none of these ideas in God's mind exist until He wills them to come into being. The key here is that God must make an act of His will before something He knows, apart from Himself, can begin to exist. So while there are an infinite number of ideas in God's mind that can exist only a finite number actually exist because He has willed them to come into existence.
You and others here have speculated as to whether God is composed of matter or energy, or light, or some other substance we know of from our own experience of the world we live in. The idea of matter and energy, because they exist, must be in God's mind, but they are not essential to Him. In other words God is not composed of matter or energy or any other substance we know of from our world, albeit, He created these substances, yet He is not these substances precisely because God is a spirit. So spirit is God's substance and as such what is spiritual is not composed, it has no parts, and therefore is not matter nor energy nor light, etc... These things exist because God is their cause but it does not mean they are somehow part of God's substance. On the contrary these substances we are so familar with are in God's mind and He has willed them into existence. So matter, energy, light and all other such substances we encounter in our study of this world are effects caused by God, who is the uncaused Cause of Aristotle... or as St. Thomas Aquinas called him, the First Cause. The effect must be in the cause or we violate reason by saying something can exist that has no cause (other than God that is, who is His own cause by definition).
Now again, in God's case, He can start with nothing and give something. In theological circles this is known as ex-nihilo... that is God created the universe of all existent things, ex-nihilo, or out of nothing. These things, more properly these beings, are ideas in God's mind initially and come into existence only after God wills their existence. Also they remain in existence only by a sheer act of God's will. As scripture hints at all of creation must be constantly in God's mind and He must make an act of His will in order for creation to stay in existence. Recall not even a sparrow can fall from the sky without God knowing it.