kaddish - Is the Talmud 100% Oral Torah?

I've been taught that the Oral Torah was passed from generation to generation from Moshe Rabbeinu. And I've also heard that the Talmud is basically a recollection of Oral Torah. This would suggest everything in the Gemara comes from knowledge that was given by Hashem to Moshe.

But I recently studied part of the Masechet Brachot in school, and one of the things we read was the importance of the Kaddish and how Hashem reacts in heaven when we say it. But the Kaddish wasn't there at the time of Moshe. How could this be part of the Oral Torah then?

Please correct me if something I said is wrong. But I really don't understand this.

Answer

As far as the main question is concerned, the Ramban in his debate with Pablo Christiani states (in the beginning of the section entitled "על האגדות") that the corpus of the Torah can be divided into three sections:

1. The Bible, in which we all have complete faith


2. The explanation of the mitzvos in the Talmud, which we also fully accept



3. The midrashim, or sermons on the bible, which we are not required to accept as part of the Oral Law, as they represent the private opinions of the person who said the sermon.

Being that a significant portion of the Talmud contains aggadic material that fits in the last category, it is logical to conclude that the Talmud is not 100% Oral Law.

With regards to Kaddish specifically, Kaddish could be considered part of the Oral Law insofar as it's recitation was an enactment of the Rabbi's, similar to the lighting of Chanukka candles or the celebration of Purim, both of which commemorate events which took place after the bible was canonized, and therefore perforce are not of the Written Law.