[Kate*]

I have never heard that grades aren't important in grad school, but here's the thing: Programs can dismiss you for both academic (usually 7 or more credits of C or lower), and non-academic (poor fit for the chosen profession despite passing grades.) That's what happened to me despite my 3.7. So, they matter a lot, but they don't in the sense that high grades won't necessarily save you from dismissal if there are other issues. Also, once you're in the field all that will matter is that you passed. I guess you could also argue that since everyone tends to fall into the same grade range, they don't tell you much about your ability compared to others.

Yes, a C is considered "failing", and any grades in the B range will probably have them voicing "concerns." It is possible to get a D or F, but the letter grade matters less at that point than the fact that you got below the C cut off.

In any given class, most people pass, a few may end up with a high C, or they will withdraw if they think they will do worse than that to save their GPA.