The idea that the apparent ignorance of Adam's whereabouts shows Adam's free will is my own; I woudn't be surprised if someone pointed that out before me, and even that I have read it somewhere, but at this point I am not aware of such point being made.
The point that all the exhortations to virtuous life in the Scripture would be pointless if man had no free will is from Aquinas: Article 1. Whether man has free-will?
The earliest definitive teaching on free will is, to my knowledge, in Irenaeus: St. Irenaeus on Free Will (Adversus Haereses IV,37)
The question is, again, why does the Bible, and especially the New Testament make so many calls to righteousness and virtue if man has no free will to choose between behaviors?
I am referring to the exhortations to love God, love the neighbor as oneself, forgive others, be kind to the lowly and needy, give example of virtue to others, avoid judging others, avoid sin even at the cost of injury to oneself, and be perfect as our Father in heaven is perfect, all made by Christ Himself. A good summary of those is in the concluding chapters of the Letter to Romans starting with Chapter 12, -- the same letter that contains several prooftexts that you used.
Can you clarify what “private interpretation” is supposed to mean to you and other Catholics, then? I am aware that it is a partial quote from I Peter, but it seems to mean something different to you than I am used to hearing from other Catholics. They use it to set aside arguments that disagree with the official positions of the Catholic Church, claiming that my view is some spurious “private interpretation” and therefore invalid. This, although it is the plain sense of the text.
You, OTOH, used it to imply it would condition a response you might have otherwise made. Advise.