Hi, thank you for your contribution.
1. "I believe that God is an invisible Spirit and created Himself a body, and that body is the body of the immortal Jesus Christ, and then God made everything through Him."
Answer: Exactly. That is what I meant to say. "And the Word was made flesh, and dwelt among us" (John 1:14). Again the Bible says, "Wherefore when he cometh into the world, he saith, Sacrifice and offering thou wouldest not, but a body hast thou prepared me:" (Heb 10:5). Also, "Who is the image of the invisible God, the firstborn of every creature:"
(Col 1:15).
So when God created man in His own image, it was in this image. That's why Jesus said "Whose is this image and superscription? Render to Caesar the things that are Caesar's, and to God the things that are God's." (Mark 12:16,17)
2. "A Spirit does not have an image or shape after all.”
I believe that a spirit looks exactly as our physical body, except see through, and that it does have a form."
Answer: Of course a person and his spirit look alike. Acts 12:15 also supports this idea (Peter is confused for his angel).
But the context of the sentence "A Spirit does not have an image or shape after all" is that it has no visible form or shape. "And the Father himself, which hath sent me, hath borne witness of me. Ye have neither heard his voice at any time, nor seen his shape." (John 5:37) However, Jesus is the visible image of the invisible God.
We read in 1Tim 3:16 "God was manifest in the flesh, justified in the Spirit, seen of angels".
3. “Also, a Spirit is dimensionless: we cannot decide which is a Spirit’s “right hand side” or “left hand side” to argue who is seated at his right hand. And a Spirit cannot cast a Shadow (for us to hide under the shadow of his wings).”
Answer: Again the context is in the literal interpretation of the word "shadow" and "right hand". We know that God is a Spirit. And whether the wings belong to Him or the Cherubim, it doesn't a literal shadow (being a spirit). When the Bible says "He who dwells in the secret place of the Most High, shall abide under the shadow of the Almighty", it means that the person will be safe, secure and protected. Shadow of the Almighty is a metaphor to a "Place of refuge".
Similarly, the intention was to say that the "right hand" of God is also a metaphor indicating His glory and power.
4. I believe that the plan for salvation was made before the creation of anything, but that Jesus was not slain before he was slain.
Answer: Exactly. When I said that the Lamb was slain before the foundation of the world, it was in the mind/plan of God. It was prophetic. Or else, How can we be predestinated in Him before the foundation of the world? God in His infinite wisdom already knew about mankind's fall, and that He would redeem them by being born as a man (Sonship).
However, we must understand that it ACTUALLY happened only in His appointed time, when Jesus was born to Mary. "But when the fulness of the time was come, God sent forth his Son, made of a woman, made under the law," (Gal 4:4)
Jesus was foreordained in God's plan before the foundation of the world, but manifest only later. "Who verily was foreordained before the foundation of the world, but was manifest in these last times for you," (1Pet 1:20)