In the first of your three NT passages, Acts 24:14-15, the late Jewish belief in bodily resurrection seems to be the connection. The verse in Daniel is very specific on this point. As far as I’m aware, though I have no specialist knowledge, resurrection isn’t mentioned, or even alluded to, in any of the books in the first two sections of the Hebrew Bible. In this case, then, I think you’re right. It clearly makes sense to infer that sometimes, at least, the term “the Law and the Prophets” was used in a loose sense to refer to all the Scriptures, including those that only came to be formally accepted into the canon many years later.
Sometimes, though not invariably. Take this verse in Acts, for instance:
After the reading from the Law and the Prophets, the rulers of the synagogue sent a message to them, saying, “Brothers, if you have any word of encouragement for the people, say it” (Acts 13:15).
I don’t think anyone has claimed that Daniel or any other books from the third section, known as the “Writings,” formed part of the readings in the synagogues in Paul’s day, or even later.
This has reminded me of something Edmund Wilson says in his book about the Dead Sea scrolls. When the evangelists and other NT authors refer back to passages in the OT that they interpret as prophecies of Jesus and his mission, all too often it turns out that the passage in the Hebrew Bible seems to have been misquoted or misattributed. According to a theory that was popular for a time among nineteenth-century Protestant theologians in Germany and Britain, the NT authors were not quoting directly from the scrolls of the Hebrew Bible or the Septuagint. Instead, they were taking their quotes from a compilation of snippets from the OT, arranged under headings such as “messianic,” “legal,” “apocalyptic,” and so on. This would explain a number of puzzling misattributions, such as this one in Matthew:
Then was fulfilled what had been spoken by the prophet Jeremiah, saying, “And they took the thirty pieces of silver, the price of him on whom a price had been set by some of the sons of Israel, and they gave them for the potter’s field, as the Lord directed me.” (Matt 27:9-10)
Part of this prophecy is in Jeremiah, but not all of it:
Behold, Hanamel the son of Shallum your uncle will come to you and say, “Buy my field that is at Anathoth, for the right of redemption by purchase is yours.” Then Hanamel my cousin came to me in the court of the guard, in accordance with the word of the Lord, and said to me, “Buy my field that is at Anathoth in the land of Benjamin, for the right of possession and redemption is yours; buy it for yourself.” Then I knew that this was the word of the Lord. And I bought the field at Anathoth from Hanamel my cousin, and weighed out the money to him, seventeen shekels of silver. (Jer 32:7-9)
This is clearly only a minor part of the OT prophecy concerning Judas, the thirty pieces of silver, and the potter’s field. The major part comes, not from Jeremiah, but from Zechariah:
[cont.]