Yes, its just impossible for any of us to say..... so much of your second question depends on the nature of your course and your research - I don't 'have' to spend any time at the uni if I don't want to beyond arranging meetings with my sup once every couple of months (it was more frequent early on) but others here have to be in every day as they are using labs, and others are somewhere between the two!
Regards teaching, I don't do any, our first years aren't allowed to teaching full stop, 2nd years and above only, but then plenty of unis and some depts within our uni allow teaching in the first year, some depts offer more teaching, some less depending on the requirements. I'm only allowed to work a max of 10 hours a week and I have a RA position in the dept so no teaching for me til this ends, some of our students will do 6 or 8 contact hours, some only one seminar a week. I know some work more than that.
It all depends on your course, your requirements, the rules in your particular dept at your uni and your funding situation
Really sorry I can't be more help