Many thanks for that summation.
I think there is a difference between the Apostolic deposit and tradition, and it is the one at which you and Fr, Simon hint. It is not clear, either from reading the NT or from the Apostolic Fathers what the relationship between Christ and the Father is, or how Our Lord is human and divine. Of course, succeeding generations made heavy weather of these things precisely for that reason. It was not unreasonable of Arius or Nestorius to teach what they taught; their positions can be supported from Scripture. But what does not support their positions was the tradition of the Church. St. Athanasius and St. Cyril both articulated positions which were not without controversy but which turned out to command the consensus of the faithful.
As ever, Fr. Simon is right to remind us that the various sources mentioned as 'tradition' should not be read apart from each other, and that they are not self-evidently transparent without guidance.
We receive the 'faith once given', but we are not to be in the position of that servant who took what he had been given buried it in the ground and returned it to his Lord as he had received it - are we?
In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. (1 John 4:10)