Your question points up the difficulty for finite creatures like ourselves speaking about an infinite Being like God and the limitations our finite state has on the language we use to talk about God. The concept of plans or planning can have meaning only in a finite context where time has meaning. But for God, what meaning can time have save as an observable state? I suppose the quick answer is "No, we did not, do not and cannot foil His "plans"" but that's not satisfactory at all because the question presumes something, planning, which is not an attribute of God, at least as we understand the word.
"Deification? I know you and Kolo have talked about theosis, becoming more "God-like". "Deification" implies an idea to me of becoming "as a God", or "equal to God". Does it go to this extent, or is it an unreachable goal?"
The concept isn't that we become God, or the equal to God but rather "as gods" as +Athanasius the Great puts in "De Incarnatione". Personally I think +Gregory Palamas describes it better in The Triads:
"Three realities pertain to God: essence, energy, and the triad of divine hypostases. As we have seen, those privileged to be united to God so as to become one spirit with Him - as St. Paul said, 'He who cleaves to the Lord is one spirit with Him' (I Cor. 6:17) - are not united to God with respect to His essence, since all theologians testify that with respect to His essence God suffers no participation.
Moreover, the hypostatic union is fulfilled only in the case of the Logos, the God-man.
Thus those privileged to attain union with God are united to Him with respect to His energy; and the 'spirit', according to which they who cleave to God are one with Him, is and is called the uncreated energy of the Holy Spirit, but not the essence of God...."
And in this:
"We unite ourselves to Him [God], in so far as this is possible, by participating in the godlike virtues and by entering into communion with Him through prayer and praise. Because the virtues are similitudes of God, to participate in them puts us in a fit state to receive the Deity, yet it does not actually unite us to Him. But prayer through its sacral and hieratic power actualizes our ascent to and union with the Deity, for it is a bond between noetic creatures and their Creator."
FK, notice how +Palamas soundly denies that we can become united with the "essence" of God. If you look at most Greek icons showing Christ, you will see the words "W WN". This name doesn't translate into English in a satisfactory way, but at base it means "The Ultimate Being or Reality" It implies that this Being is beyond any existence we comprehend and is the source of everything out of nothing. Thus the Cappadocian Fathers, as I am fond of remembering, said "I believe in God; God does not "exist"." For this reason we as created beings cannot share in His essence but can only share in the divine likeness (have union with the divine energies or put another way, experience and exist within the divine, uncreated light) through theosis. To believe otherwise would be some sort of Hinduism or Buddhism.
I fully agree with you that language can get in the way here. Did God create time itself, at least in part, for us to experience? Our knowledge of Him is in the context of time, so regardless of whether He does or does not experience time, we are meant to experience it and relate to Him through it. I think God wants us to understand Him to the extent of the abilities He gave us (including in time), even though we are not capable of understanding the full picture. Therefore, I believe this is a legitimate topic.
For me, this debate has been on whether or not God "changes His mind" in the way we experience time. Does God "react" to external stimuli (human actions) and do something different? While reiterating that God is not the author of evil, I would say that everything that has been, and is yet to be was pre-ordained by God in the beginning. The idea that God alters or changes His "plan" based on what humans do implies to me an admission from God that He was wrong about something. Tongue-in-cheek, I ask is God only human? :)
FK, notice how +Palamas soundly denies that we can become united with the "essence" of God.
That is the distinction I was "hoping" for, thanks for the clarification. :) I suppose this is another, accidental, example of language getting in the way ("as gods").