In an attempt to answer to your questions:

1: Yes, it would. The “second generation” addressed in Deut. is most likely the exiles in Babylonia. The real author(s) of Deut., written during the exile, rehearsed the wanderings in such a way as to warn the exiles that they may well find themselves in another foreign land should they not return faithfully to the law. How we would use that to inform us of Jesus’ use of Deut. escapes me.

The questions is not, did Jesus understand himself as functioning as the second generation, but did Matthew who constructed this incident for his own purposes.

I also find MacIntyer thoroughly dependent upon non-critical approaches to the canon. It seems he actually believes Moses wrote Deut. Consequently, he works in an atonement theory by a huge expansion of the intention of Matthew.

2. Regarding progressive revelation: My post on Sensus Plenior: Legitimate or Smoke and Mirrors?
https://faithontheedge.org/sensus-plenior-legitimate-or-smoke-and-mirrors/

3. Peer review is the only thing that comes to mind. We should also consider that authorial intent is not the only criteria we can use for interpretation. Even that is often nothing more than attempted mind-reading.