There's a lot to cover. Here is what the Orthodox Study Bible has to say about this:
God the Father made heaven and earth. The mighty wind is the Holy Spirit. He proceeds from the Father, and is the Lord and Giver of Life. Since He is Lord, He is coequal with the Father, and is His Coworker in making heaven and earth. God the Father spoke to His Word and Only-begotten Son, through whom He made the light. Since the Son, too, is Lord, He is coequal with the Father, and is His Coworker in making heaven and earth. The Father made heaven and earth through the Son and in the Holy Spirit. Since the Father and the Son and the Holy Spirit made heaven and earth, They also made everything mentioned in these verses. The Holy Trinity also made man. God the Father is speaking to God the Son, and He uses the personal pronouns Us and Our. These pronouns indicate three distinct Persons: the Father, the Son and the Holy Spirit. The word image is in the singular, and shows the three distinct Persons of the Holy Trinity are one in nature and undivided. For it does not say, "Our images". Therefore, the Holy Trinity is one undivided nature in three distinct Persons.
Seth was begotten from Adam and Eve. This threefold relationship illustrates, to a certain extent, the Holy Trinity. Adam had no human father. He was begotten by no one. Thus, he was unbegotten. Seth was begotten from Adam. Eve was neither unbegotten nor begotten, instead she proceeded from Adam. Therefore, Eve and Seth were related to the unbegotten Adam, but each in a unique manner - Eve proceeded from Adam, but Seth was begotten from him. Each person had his or her own distinct and unique properties - unbegotten, begotten, and proceeding - but all three possessed the same human nature. Similarly, the manner in which these three existed images the Holy Trinity. God the Father is Unbegotten, God the Son is begotten from the Father, and God the Holy Spirit proceeds from the Father. These unique and distinct properties - unbegotten, begotten, and proceeding - distinguish each of the individual Persons of the Holy Trinity from each other; yet, They are one in nature.
The pronoun Us refers to the Holy Trinity. The words go down are a figure of speech, for the Trinity is everywhere present and fills all things. The words "came down to see" are also a figure of speech, for the Trinity is not ignorant of anything. God condescends to our weakness that we may understand something about Him and His works.
The Holy Spirit spoke through the prophet Moses, who wrote this Scripture. Thus the Holy Spirit preached the gospel beforehand to Abraham ("In you all the nations shall be blessed"). The Holy Spirit inspired Moses to write that the Lord said to Abram this scripture. Who is this Lord? He is God the Father. Thus, the Father preached the gospel beforehand to Abraham. The Holy Spirit inspired Moses to write that the Lord appeared to Abraham and spoke to him. Who is this Lord who appeared? The Holy Spirit identified Him in Genesis 15:1 as the Word of the Lord whom Abraham saw in a vision, and He identified Him as the Angel of the Lord in Genesis 16:7, 16:9, 16:10, 16:11 and 16:13. This Word is the Son of God and the Angel is also the Son of God, for He was no created angel. He is called Angel because He alone reveals the Father. Thus, the Son also preached the gospel beforehand to Abraham, for the Father always speaks through His Word. Therefore, where one Person of the Trinity is present and working, the other two Persons are also present in one and the same working for the salvation of man. The Father works through the Son and in the Spirit.
The God of the everlasting covenant is the Holy Trinity, for the Son is God of God, the Only-begotten of the Father. The Holy Spirit is also God of God, for He proceeds from the Father.
The Holy Spirit spoke by the prophet Jacob, who identified the Angel as God. He is the Son and Word of God. For no created angel could redeem Jacob from all evil. Therefore, the Holy Trinity is revealed to a certain extent in the Old Testament, and fully in the New.
The Lord our God is the true Son of the true Father; thus we do not worship any false god. However, false gods do not exist in themselves, for this commandment refers to the future, and what is in the future does not yet exist. But the Son is true God of true God; therefore, He exists eternally with the Father and the Holy Spirit. We worship the Father and the Son and the Holy Spirit, our one God.
This is the Angel who said to Moses, "I am who I am" (Exodus 3:14. He is the Only-begotten God, because He is begotten from the Unbegotten Father before all time and ages. He is called Angel to distinguish Him from the Father. The word angel means messenger, and this Angel reveals the will of the Father to man. Moses believed in the Holy Trinity. Thus, "My" refers to the Father, and "Angel" refers to the Son. This Angel has the authority to forgive sins, for the Father's name is in Him. The Father's name is the Lord, therefore, the Son is also called by this name.
The Son of God is the 'I am', the Lord God of Israel (Exodus 3:14). He is one of the three Persons of the Holy Trinity.
The spirit is the Holy Spirit, one of the three Persons in the Holy Trinity.
Moses aknowledged Christ as the God of the spirits of all flesh, and therefore, so are the Father and the Holy Spirit. For the three Persons are one in essence and undivided. The spirit is the Holy Spirit.
There is only one God, because there is only one divine essence or nature, which is undivided. For God is a name indicating the divine essence. This undivided essence exists in three Persons - the Father, the Son, and the Holy Spirit.
By Moses saying "the Lord alone", we understand the simple, blessed and incomprehensible essence of God. Moses is not saying the one Lord is one solitary person. Rather, he is saying He is one undivided essence or nature. For person and nature are not the same thing. The divine nature exists undividedly in three distinct Persons: the Father, the Son, and the Holy Spirit. The Son is begotten before all time and ages from the essence of the Father, but His begetting does not divide the Father's essence. The Holy Spirit proceeds before all time and ages from the Father, but His procession does not divide the Father's essence. The Persons are distinct or different, but the essence is one and undivided.
To serve the Lord means to worship Him. But how can we worship the Father if we, so to speak, sever the Son and the Holy Spirit from Him?
I have only covered the Pentateuch (Torah) so far. I will address the other books of the Old Testament tomorrow.