I don't think the critical point was His ascension, but rather His resurrection. Through His birth, He had become a real human being, 100% human. He could do no miracles; rather,the Father did the miracles THROUGH Him, just as He created the universe through the Son. So while Jesus was a human being, His personality was confined to His body. He said,"... I tell you the truth: it is to your advantage that I go away, for if I do not go away, the advocate (paraclete) will not come to you; but if I go, I will send it to you." (John 17:7) As I see it, after Jesus was resurrected, He could then send His personality anywhere in the universe. He "became a life-giving spirit." (1 Cor 15:45).You wrote:1. Why did Jesus have to ascend before his spirit could leave his body? Do we have reason to believe there was a change that occurred to him after ascension?
Perhaps someone will object to my translating "αυτον" as "it" rather than "him." This Greek word is masculine, not neuter. So how can I translate the word as "it"? In Greek the gender of a pronoun agrees with the gender of its antecedent. And the antecedant of "αυτον" is "παρακλητος" (paraclete) which is a masculine noun.
However, I have no problem with "I will send him to you" since the spirit of Jesus is personal, and IS, in fact, Jesus, and Jesus is a "him." Yet, as far as I know, there is nothing in the Greek language itself that constrains us to refer to the spirit of God as "him" rather than "it."
No, I am not aware of any. My view originates from my own reading of the New Testament, and of Justin Martyr's "Dialogue With Trypho."2. Are you aware of any books that go into this in more detail?