In the US, PhD programs will usually be combined with the Masters, and will start with ~2 years of coursework. This can cause no end of communication issues when discussing how far one is along a PhD.
Can you leave with a Masters after two years then? I was vaguely aware that Grad School in the US wasn't quite equivalent to here. I went straight from my undergraduate to my PhD, but I guess because of the earlier specialisation that the second half of my undergraduate was vaguely similar to a Masters in the US say.
Yes, but there isn't that much of a point to it. For fields where the terminal degree is a Masters (e.g. Master of Fine Arts, Master of Business Administration), there's usually some jobs that will require them. For fields where the terminal degrees is a PhD (e.g. STEM fields), there isn't much you can do with a Masters that you couldn't have done with a Bachelors.
Yes, granting a Masters after the completion of required coursework is commonplace on the way to a PhD, regardless of whether you leave or stay in the program.