Nick asked for patristic support for the quotations he identified in Question 1. With the word limits it is impossible to identify all the relevant quotations or address every facet, but several quotations should illustrate the same kinds of thoughts:
Augustine – On the Trinity – Book IV, Chapter III:
6. Therefore on this double death of ours our Saviour bestowed His own single death; and to cause both our resurrections, He appointed beforehand and set forth in mystery and type His own one resurrection. For He was not a sinner or ungodly, that, as though dead in spirit, He should need to be renewed in the inner man, and to be recalled as it were to the life of righteousness by repentance; but being clothed in mortal flesh, and in that alone dying, in that alone rising again, in that alone did He answer to both for us; since in it was wrought a mystery as regards the inner man, and a type as regards the outer. For it was in a mystery as regards our inner man, so as to signify the death of our soul, that those words were uttered, not only in the Psalm, but also on the cross: "My God, my God, why have You forsaken me?" To which words the apostle agrees, saying, "Knowing this, that our old man is crucified with Him, that the body of sin might be destroyed, that henceforth we should not serve sin;" since by the crucifixion of the inner man are understood the pains of repentance, and a certain wholesome agony of self-control, by which death the death of ungodliness is destroyed, and in which death God has left us. And so the body of sin is destroyed through such a cross, that now we should not yield our members as instruments of unrighteousness unto sin.This quotation provides an example of the basic concept behind the “Reformed” quotations Nick provided: Christ’s one death substitutes for our two deaths. I’d love to provide many more quotations from Augustine, who consistently refers these words to Christ speaking on our behalf, as our substitute, and the representative of the old man. These may be found, for example in his Expositions of Psalms 22, 38, 42, 44, 50, 71, and 141. The issue of wrath, in particular, being on this representative head may be found in his exposition on Psalm 88: “Over that Body, which constitutes the unity of the Saints and the faithful, whose Head is Christ, go the wraths of God: yet abide not: since it is of the unbelieving only that it is written, that ‘the wrath of God abides upon him.’”
The one death therefore of our Saviour brought salvation to our double death, and His one resurrection wrought for us two resurrections; since His body in both cases, that is, both in His death and in His resurrection, was ministered to us by a kind of healing suitableness, both as a mystery of the inner man, and as a type of the outer.
Leo the Great – Sermon 68:
Jesus, therefore, cried with a loud voice, saying, "Why have You forsaken Me?" in order to notify to all how it behoved Him not to be rescued, not to be defended, but to be given up into the hands of cruel men, that is to become the Saviour of the world and the Redeemer of all men, not by misery but by mercy; and not by the failure of succour but by the determination to die. But what must we feel to be the intercessory power of His life Who died and rose again by His own inherent power. For the blessed Apostle says the Father "spared not His own Son, but gave Him up for us all;" and again, he says, "For Christ loved the Church, and gave Himself up for her, that He might sanctify it ." And hence the giving up of the Lord to His Passion was as much of the Father's as of His own will, so that not only did the Father "forsake" Him, but He also abandoned Himself in a certain sense, not in hasty flight, but in voluntary withdrawal. For the might of the Crucified restrained itself from those wicked men, and in order to avail Himself of a secret design, He refused to avail Himself of His open power. For how would He who had come to destroy death and the author of death by His Passion have saved sinners, if he had resisted His persecutors?Leo the Great, unlike some of the other fathers, is willing to acknowledge that there is a sense in which Jesus was forsaken by the Father, though (of course) this was voluntary (as the Reformed acknowledge)
John of Damascus - An Exposition of the Orthodox Faith (Book IV):
Others again are said in the manner of association and relation , as, My God, My God, why have You forsaken Me? and He has made Him to be sin for us, Who knew no sin, and being made a curse for us; also, Then shall the Son also Himself be subject unto Him that put all things under Him. For neither as God nor as man was He ever forsaken by the Father, nor did He become sin or a curse, nor did He require to be made subject to the Father. For as God He is equal to the Father and not opposed to Him nor subjected to Him; and as God, He was never at any time disobedient to His Begetter to make it necessary for Him to make Him subject. Appropriating, then, our person and ranking Himself with us, He used these words. For we are bound in the fetters of sin and the curse as faithless and disobedient, and therefore forsaken.John of Damascus appears to be recognizing that these words are spoken in Jesus’ appropriated role as our representative: receiving (and expressing) the forsakenness we deserve for our sins.