[imardmd1]

None of the arguments you've advanced to discredit Paul as the author of the letter to the Hebrews are very strong. An argument very difficult that opposes yours, taken from A Consideration Of The Attestation Of Scripture To The Authorship Of Hebrews" (click here)

In a nutshell:

A. Both of Peter's letter are, according to his ministry to "the Circumcision," addressed specifically and narrowly to the Hebrew Christians scattered in the Diaspora, and in the very provinces that were the core of Paul's church-planting efforts.

B. In 2 Peter 3:15 Peter writes:

And account that the longsuffering of our Lord is salvation; even as our beloved brother Paul also according to the wisdom given unto him hath written unto you^plural; 

This says that Paul did write to these same Hebrews in the same area.

C. Furthermore, Peter says also that what Paul wrote to them as no just a note, but inspired Scripture according to the wisdom given to him, necessarily by God the Holy Ghost:

As also in all his epistles^{which were later agreed to be canonical}, speaking in them of these things; in which are some things hard to be understood, which they that are unlearned and unstable wrest, as they do also the other scriptures^{OT, of equivalent cananicity}, unto their own destruction. 

Paul's other writings were specifically toward particular individuals or particular churches, but Peter equates them as inspired writing.

D. So it may be postulated that: (a) Hebrews is a document that was addressed to the same kind of narrow audience as Peter's was; (b) Paul was a recognized author of inspired Scripture; and (c) therefore Peter is essentially saying that Paul is the author of the Hebrewa letter.

Well, this might be interpreted that the Christian Jews in the mixed churches of Asia Minor were conjointly addressed with the Gentiles in the church by the same epistles, and thus a part of Peter's "you". But what other writer is a Sanhedrin-bent qualified Hebrew scholar and apostle of the first or second water capable of explaining the NT mysteries hidden in the OT but revealed by inspired interpretation in the New?

[HarleyD]

So it may be postulated that: (a) Hebrews is a document that was addressed to the same kind of narrow audience as Peter's was; (b) Paul was a recognized author of inspired Scripture; and (c) therefore Peter is essentially saying that Paul is the author of the Hebrewa letter.

I would say your logic is flawed.

A) The letter of Hebrews isn't to a "narrow audience". It is a letter to all Hebrews.

B) It is refreshing to hear a Catholic claim that Paul's writings was inspired. It has been my experience here that not all Catholics believe that. Be that as it may, the mystery of who wrote Hebrews doesn't make it any less inspired. We certainly wouldn't say Ruth, Esther, Job, Jonah, etc. aren't inspired even though we don't know who the author is. There are many inspired writers, not just Paul. Some we know, some we don't.

C) I see nowhere in the letters of Peter where it claims Paul wrote Hebrews.