I have always heard that Rabbi Yehuda Hanassi "compiled" the mishna. What were his roles in compiling it in the form that we currently have it? Specifically, did he perform any of these roles:

* writing the text itself - all / most of it? Any specific parts he wrote vs. others?
* editing what other wrote. Who else wrote?
* leader / manager, i.e. - telling others what to write or include

The above is not an exhaustive list. There are probably other roles that I can't think of, now.

Along with this, what decisions determined what and who was included and what / who was excluded. After all, we have *braitot*, so a lot didn't make the "cut" for some reason. What decided it?