Ohh juggling between comics, social life and uni/work is my favourite extreme sport
I used to draw two series when I was in uni (studying chemistry ) and during my first two jobs, then I had a very long break, and now I'm continuing with my main series while still having a job. Mind you, my advice might not be the best as I had a terrible burnout causing me to stop drawing comics for 3 years, but that might be mostly because my job was quite stressfull at that time (...and we were doing lots of extra hours). Now I'm back to drawing and I'm using the same methods as before and it's perfectly fine, so maybe changing the job was the main success factor here cx
1) I guess every artist has their own workflow that works the best for them. For me, I have a basic list of main events that are supposed to happen in the story. The list also has notes like which day it is for my characters, and the moon phase (just so I don't draw a fullmoon on every single night sky panel). Then I do storyboarding for one chapter at the time- just a small thumbnail of how the page is supposed to look like, and dialogues below the page. Tbh I don't really like this part of creating comics, so I don't do a lot at once- just planning 1-2 pages a day. Usually when I'm drawing chapter X, I'm already slowly sketching + drawing frames for chapter X+1, and slowly planning chapter X+2. This way I can review my chapter storyboard twice- when sketching and later when I finally start drawing.
2) I think that depends on how good are you with memorising stuff and learning, and also how much work is your uni giving you. AND how well do you want to do in uni, so it's hard to tell. But I think you shouldn't worry too much about it- drawing can be a nice relaxing break between studying. As long as you have a buffer for days when you can't draw at all, you should probably still find time for drawing on less busy days.
3) I'd do that the other way round- not setting number of pages per week, but adjusting your updates to how much time you have. Think how many pages you can realisticaly draw during a week (remember about studying, eating, a good night sleep and some activities like taking a walk), and reduce the number to consider 2-3 days during which for whatever reason you won't be able to draw at all. If by any chance you draw more, that's great, that makes a bigger buffer.
What worked for me in uni (and my 9-5 & 14-22 jobs) was drawing in the morning. If my classes started at 9 or later, I'd wake up early enough to spend about 1h drawing. Then I wouldn't have to worry that I'd be too tired to draw when I come back home. Also having a good teamwork with other students works wonders when it comes to time management (notes exchange, studying together etc).
And even during busy days, I'd try to do at least SOMETHING for my series. It might be just one panel, or just a sketch for one next page, or a lineart for one character on one panel- even if it's 5 minute work, it's something cx