Wow, awesome and very deep questions, Lonnie.
The Bible tells us that God is "from eternity and to eternity"; He existed before time was, which is a fact the human mind cannot comprehend. We are not told in the Bible how many creations, worlds, or universes there may have been- the Genesis account relates to the current earth and its creation. Time, as such, is only related to this universe and is not necessary in a past or future eternity.
Why did God create humans? There may be many answers to this, but the Bible account relates how God had a plan to bring into being a creation that could have a relationship with Him (The Creator). As part of His plan, God will dwell forever with mankind and enjoy each others' presence for the rest of eternity. All those who choose to accept God's terms (faith in Christ) will be included in that world where we shall dwell with Him when 'time shall cease to be'.