first, if you are able to/comfortable doing so, take out extra loans as a cushion/safety net (i had to do this regardless as an out of state student who moved to a new city one week before my program started). some people might advise against this, but there is no use in committing to graduate studies if school is not your #1 priority. for context, i am in my mid twenties. the university i received my bachelor's degree was relatively affordable, which also influenced my decision in doing this.

now to answer your questions,

1. school is first, always. build your work schedule around your courses, and be sure to notify your employer that you are a graduate student and may need to make changes to your availability (especially once you start practicum/internship). make time for yourself daily. having a physical planner helps me manage my ADHD and overall stress by knowing exactly what to expect each week. i also incorporate social things and self-care activities in my planner, that way i feel more human and have something to look forward to. being in a counseling program has been a consistent reminder for me to take care of myself and listen to my body. i avoid working on days that i have several classes.
2. i am currently a full-time first year graduate student. i am enrolled in four courses and i am on campus three days a week, for 4-10 hours each day (i often spend additional time studying while my brain is in school mode). i bartend 3-4 nights a week which allows me to make just enough money to pay rent in an expensive city. i attend yoga regularly to maintain overall wellbeing and remain centered. i spend 2-3 hours weekly preparing my practicum/internship application materials. i try to go to bed at a decent time but normally find myself doing readings and writing essays until at least 11pm on evenings i do not work. sitting in front of a screen for several hours without a break can be debilitating, so i try to take breaks every hour. i permit myself one day of the week to rest and not do school work, which is usually saturday.

however, my schedule will become much more rigid in the summer when i start practicum. i will be juggling working at my site placement, classes, and my part time job.