In Platonic philosophy and a few others I think, there is a duality between becoming, which encapsulates the physical world, humans, things that change and grow, and being, which is what these thing are growing towards, that which is ideal, perfect, complete, and unchanging in that it has reached the fullness of existence so to speak, which is understood by many philosophers as God. In that sense, God is being itself, because God is the eternally present perfection of ideals.
As far as personal musings and understanding, yes, God is present in all of His Creation, which is also how I understand the phrase “all Creation glorifies the Lord.” In all of creation, aspects of God are present. A fairly obvious example is the beauty of a sunset. To those who know how to see it, in a sunset, one can perceive aspects of the Beauty of God. Also, God both creates and sustains all of creation, so in that sense He is also present in everything.
The “heaven and earth” topic is more related to the limitations of human language to fully express ideas. Also, I’m pretty sure than in some places, it literally just means the Earth and the sky/stars/universe, and then in others means Heaven and Earth. Although sometimes I also think earth in the Bible refers to the physical universe in general. I’m not sure though. I’d have to see specific examples.