(1) I believe academic performance, and hence progress, is heavily dependent on balance. I think the very common issue of breaking down due to "stress" (loosely defined term but everyone is using it anyway) is, at the end of the day, a matter of discipline: not having a set of strict rules regarding your "duties" towards taking care of your body. We are only as strong as our weak link, so if the body falls, our brains will too (Mens sana in corpore sano, right?). One of the most important "rules", I think, is being strict on taking breaks. Our bodies did not evolve to sit down for 8 hours, and your cognitive performance declines pretty rapidly if you don't move around. Here is one of the many papers backing the "disciplined" breaks method:
https://bpspsychub.onlinelibrary.wiley.com/doi/full/10.1111/bjep.12593I personally use a 25 min approach, with a 5 min walking/ squeezing something, etc...
(2) Questions:
(a) I would like, once my research proper has started, to spend more time with my little brother (not in Vienna). How flexible is the PhD path in this regard? (after I finish taking credit classes, of course)
(b) How much interaction with a supervisor is the norm? 1h per week? More? Less?
(c) Is it advisable to do a semester abroad? Is it even part of the program?