Are you asking as a prospective grad student, current grad student, or someone who is about to have their first grad student?
I'm sure everyone is different, but in the first semester of my masters I took 3 courses and did an independent study (which was along the lines of what locutus said - good enough for a poster at a conference, not good enough for a paper- due to data limitations in my case). I was more or less handed the project my masters was on, so the second semester I did all the prep for the field work and did the experiments (and took two courses).
The first year of my PhD I worked on odds and ends for my advisor while developing my dissertation project (which was done jointly with my advisor) and taking a few courses.
I never TAed until the fourth year of grad school and I mostly did that as a favor and to get a teaching line on my CV and by then I was done with my own courses.
In addition to what research they are doing, if they are taking courses and teaching, what are the time expectations?
I think this is where it gets tricky. If your paycheck comes from TAing, not from your advisor, I think your only research obligation is doing what you need to do to keep your research moving along, especially when you have coursework that needs to get done too. It's totally different if your advisor is paying your salary for research (which was always my case, except when I was on fellowship, in which case it was functionally the same).