Those scriptures you quoted (while they do not in any way contradict the biblical doctrine of the deity of Jesus) are some of the key scriptures we use daily to support the Biblical doctrine of the oneness of God.
As far as Isaiah 9:6, At best you could say "god" in Isaiah 9:6, doesn't necessarily mean the one true God, but could refer to him as "god" in the same sense as "mighty men" or "angels". This is an acceptable argument given the definition behind "el". There would be no reason for me to argue against that (as "el" can refer to human or divine). I'm simply pointing out where He is referred to as "God", when you said He is not. Any attempt to say this verse isn't referring to Him as "God" (regardless of the definition you use), would be twisting the plain reading of the scripture. This verse is not a proof text that the Messiah is YHWH, but it does refer to Him as "God". You can also tell me that "Everlasting Father" should actually be translated "father of eternity".
But, like I said, I can provide biblical evidence to support the deity of Jesus, and to demonstrate that He is the YHWH of the Old Testament. This verse (Isaiah 9:6) is not one of them (and I never said it was, and never tried to use it as one). It only shows that He is referred to as "God", when you said He is not.
I understand the arguments you are trying to use, as I've heard them all... You want to point at old testament names, and what they mean. I've already addressed this. You pointed out Joshua of the OT. The name "Jesus" (or Joshua) is not what makes someone God. Jesus being called Jesus is not the proof that Jesus is God. It's the reason scripture gave us as to why He is called, "Jesus" that is so significant. "His name shall be Jesus (Jehovah saves)" WHY??? "FOR HE SHALL SAVE HIS PEOPLE FROM THEIR SINS" .
Again, who is saving people from their sins?
But then it goes further. We don't hinge everything based on one verse.. He is called "Immanuel" (God with us). This fits right along with scripture... John 1,1,14 demonstrates that God (who is the Word), became flesh. 1 Timothy 3:16 "God was manifested in the flesh" (yes, I'm well aware of the arguments you will try to use).
Someone can try to "write off" one scripture, and twist and turn... But when scripture after scripture after scripture confirms the same thing, it becomes MORE than a mere coincidence. It becomes more than just a fluke. It becomes more than just a misprint. It's the truth found throughout the Bible.
The Biblical message is clear. God is one. And Jesus is this one God. One verse alone doesn't confirm this. Countless amount of scripture confirms this, and it takes a lot of fancy footwork and sidestepping to try to discredit them all.