Since you understand this, then why did you ask your initial question (is not the Talmud an "up-dating")?
It was a response to what you said in #4.
Talmud is commentary, primarily about the mishnah and it contains the text of the mishnah but there is also commentary on the Tenakh and other subjects.
Where as the Torah contains commandments, the Oral Torah sets out how to accomplish these mitzvot. It was not supposed to be written and only the most dire circumstances forced the Rabbi's to commit it to paper.