I have some points to discuss:

1. The Major and Minor Prophets of the Bible contain a significant amount of data from other persons, namely, editors and others whose words were added without acknowledgement. Those additions include materials such as superscriptions at the beginning of books (e.g., Isa. 1:1); descriptions of events (e.g., Jer. 7:1-15//26:1-24); and even “updates” of prophetic messages to apply them to new situations (Hos. 1:7).

True.  Christian scholars are well aware of these facts.  There are many more examples that one can provide.  I do not see why this is a problem.  These books are inspired and authoritative.  Like Peter said, the writers of these books, including the “editors and others” “were carried along by the Holy Spirit.” (2 Peter 1:21).  I simply do not see any theological or doctrinal problem created by the apparent fact that editors put many of the Old Testament books into their final form.  If you have a specific example where you believe that such “editing” is problematic to the idea of biblical inspiration or inerrancy, please let me know, but I know of none.  This is true but not problematic for Christianity.

2. In the case of several books, we have no information about such persons: Joel, Obadiah, Nahum, Habakkuk and Malachi are names only. This is strange if there is a continuous tradition of preserving their words. Why was the information so scant? And why has it not been preserved elsewhere in the Hebrew Bible?

Again, true.  In fact, we do not know who wrote Joshua, Judges, 1 & 2 Samuel, 1 & 2 Kings, 1 & 2 Chronicles and we do not know who wrote many of the Psalms.  What is important is that these books are inspired by God, and I am convinced, due to the evidence, that Malachi, Joel and other books are inspired by God.  Again, you are telling me something that I and all Christian scholars are well aware of.  This is not “news.”  So, my response is this:  Why is this a problem?  These books are inspired by God.  I look at the prophecies in Joel (2:28-32) and Malachi (3:15, 4:5-6) and see true marks of inspiration.  Their words were preserved because the Jews in their time recognized these as words of inspired prophets.  The almighty God entrusted the process of canonization of the Hebrew Bible to the Jews.  I trust God, and I believe that all these scriptures are inspired by God (2 Tim 3:16), and that is all that is needed.  It was not normal in ancient times for authors to sign their work.  This is a cultural thing.  That is why these documents are not signed. This was also true in the New Testament gospels.  We cannot ask people in the ancient Near East to behave as we in the 21^st century would expect them to do.  This explains why we do not have biographies of the authors attached to Joel, etc..

3. Not all the words of the canonical prophets were fulfilled. The Northern Kingdom (Israel) was never restored, for example, in spite of the hope that Jeremiah expressed (Jer. 3:18), and the Temple built after the exile was not equal to the one of which Ezekiel dreamed (Ezek. 40—42).

There were a number of provisional prophecies in the Old Testament.  In Samuel 7:14 there is a prophecy that the Jews would never fail to have a king on the throne, but that prophecy is conditioned on the faithfulness of the Jews. Deuteronomy 28-29 is loaded with conditional prophecies.  We cannot demand that conditional prophecies be treated as unconditional ones.  What we need to do is look at every prophecy on a case-by-case and ask reasonable, fair-minded questions about these prophecies–as to whether they were conditional.  Isaiah 53 is not a conditional prophecy!  Micah 5:2 is not a conditional prophecy.  But, clearly, some of the prophecies surrounding the destruction of the Northern and Southern kingdoms and their restoration were conditional.  BTY, Ezekiel 40-42 is a different sort of prophecy.  Really, it is better described as a vision than a prophecy.  It is a vision which is pregnant with symbolic meaning, not only about a restored Jewish temple, but also about the future kingdom in heaven.

4. Deuteronomy 18:21-22 declares that an oracle that is not fulfilled is one the God did not speak; Jeremiah gives fulfilment of peace prophecy as a criterion of genuine prophecy (28:9). It was a criterion of limited value, however, for fulfilment was often long in coming, as Jeremiah’s contemporaries derisively pointed out (17:15).

My response to this is pretty much what I already said about point #3.  Every oracle, vision and prophecy needs to be taken on its own and analyzed for itself.  Deuteronomy 18:21-22 is a statement about a particular kind of prophecy, which is one about which the prophet says that this particular thing will happen at this particular place and at this particular time.  If it were not, it would not have been a useful statement.  We can assume a commo-sense approach by the Jews to this statement.  I certainly agree with what Jeremiah said in Jer 28:9.

What is your opinion?

Naveed.