Hi Doug, just a quick note on a date for The Letter to the Hebrews, I read somewhere that there is similar Theology evident in it to that of 1 Clement, so at the earliest it would have been written right at the end of the 1st Century. This is just the view of one guy obviously.
The content of Hebrews itself seems to concentrate on the Salvation that it claims Christians have attained, and the need to hang on to it, not to slip in to Apostasy, and is not overly concerned with Jesus as a messiah.
But obviously it agrees with the 4th Gospel that Jesus was Divine in a sense, and thus able to enter heaven and be a mediator and Saviour. Only someone "anointed" by god in some sense could do that. It certainly seems to be addressed to , if not exclusively a priestly Class, certainly Jewish Christians well versed in the ideas found in the Hebrew Bible, and thus able to appreciate the Theological arguments.