I'm not sure how it factors into admissions, but as someone who also worked ~30-35 hours per week on top of school, I kind of wish I hadn't. It feels fabulous to graduate loan free and debt free - I can basically start saving right away - but, it does come at a cost (i.e. less focus on school). You can pay off a small loan (< $5k) pretty fast. And it's worth it, I think, to be able to focus on physics and physics alone, because if you're a weak student because you worked a lot, grad. admissions will probably not work in your favor, whereas if you're strong, you will probably get more money as a graduate student, and be able to pay off debt more quickly. I'm not suggesting people don't work or that they take out massive loans, just that you might consider doing 1-2 semesters work-free so that you can really, really focus when it's most important. (if that's possible. My school has cheap tuition, less than $3k a semester, so maybe most of you can't do that... I don't know).
I should've taken a loan for my last two semesters, studied really hard for the PGRE and my classes. I'd only be a few thousand dollars in debt, but probably would be in a slightly better position for grad school now, and with more strength in my undergraduate physics and math - I could've gone so much further in research and deeper understanding if I hadn't been working so many darned shifts... thank goodness graduate school will be my only job for the next few years
you can pay off (small) loans later, but you only get one shot at being an undergraduate.
just my 2 cents.