Dave, these are good questions, and if someone else was saying the same things I have been saying in this thread I would use the exact same scriptures in response
The Apostle Paul was fully aware of what it meant to be "in Christ", as opposed to "Christ being in him". Being in Christ Paul knew he was always in the Fathers presence because he was the one who revealed to us in scripture that "we were raised with Christ and are sitting in Heavenly places in Christ." (Eph 2:6) This was the same person who said that he would come to visions and revelations of the Lord, and when did he could not tell if he was still in his body, or out of the body. (2 Cor 12:2-3)
Paul also understood that his physical body could never allow him to gain access to God's Heavenly Kingdom because it is tied to, and limited to this earth only.
Jesus knew that his Father was in Heaven, but also knew and understood that it was his Father inside himself that was speaking through, and performing the works that Jesus did. God in Heaven, and on earth reconciling the world unto himself. Jesus told us that his Father was inside him, and he was inside his Father all at the same time.
No difference with Christ being in us, and we being in him all at the same time. We being in Heaven and on earth. On earth, our bodies are separated from God in Heaven above, but thank God we walk by "faith", and not by "sight". If we keep walking by our physical senses of the flesh we will always seem to separate from God. As long as we are at home in the body (walking in the flesh) we are away from the Lord, but we are not in the flesh, but in the Spirit where we can come into his presence at any time while living in a fleshly body.
When our physical body dies so do all of our physical senses that could never come in contact with the Lord. Paul desired to depart from his body so that he could enjoy his unbroken fellowship with God without any hindrance of his flesh.