I still have a rather large slab of Augustine and Hilary to read, but I've now read a rather large amount of Patristic writing related to the Trinity. Here are some observations:
1. Proverbs 8:22 figures extremely large in debates with the Arians. A large part of this rests on the LXX. I think it's Gregory of Nyssa who at least raises the point that the Hebrew is 'acquired' and not 'made'. Nonetheless, the Father's extensive treatment of this verse shows how concerned they were to (a) defeat the Arians, (b) integrate the Scriptures, (c) develop hermeneutical principles that worked.
2. The hermeneutical key that emerges is primarily Christological, and involves referring anything that seems to lessen or diminish Christ to the Human Nature, and statements of equality to the Divine Nature. This principle also leads them to pay careful attention to the timing of reference of statements, and to refer some to the eternal relations of the persons, others to the economy of salvation.
In doing so, I'm convinced they're largely right. No one I know speaks, or writes, this way anymore. Probably, I believe, because of a fear of sounding Nestorian. Nonetheless, it's useless to claim to play by a Nicene/Chalcedonian ruleset, and then sideline the exegetical basis entirely. This, I suspect, is what gets some moderns in trouble.
Mt 24:26 remains a major problem for the Fathers, because the verse doesn't qualify 'the Son', and that is their major indicator for whether something should be qualified or not. In this I think they are too zealous for lexical precision. Just as I think they often get 'Son of God' wrong in meaning, and 'Son of Man' too.
Nonetheless, one has to grapple with death by 1000 paper-cuts - one cannot consistently sideline Patristic exegesis, and in each case maintain that the whole remains in-tact. If one whittles away all such supports, the structure will fail.
3) The Fathers work with a recursive methodology. Their conclusions about ousia, hypostaseis, the Trinity etc., all emerge from a careful reading of the Scriptures. There is no doubt in my mind that a careful and responsible reading of the NT leads to the conclusion that the Son is God, the Spirit is God, the Father is God, and the Father is not the Son, etc.. It's with that in mind that the Fathers move to theorising, as best they can, the relation of nature to person, and so developing principles like Athanasius', that the Father and Son share everything except what it is to be Father and to be Son. Then, it's the movement back to integrate seemingly troublesome scriptures into the theory that has been developed.
4) John's Gospel is indeed the trinitarian textbook for the Fathers. And rightly so.
5) Classic Trinitarian formulations stand the test of time.