Yuck! Gluten plus PUFAs from the oil? No thanks!

I'd go for the ice cream if the dairy is antibiotic & hormone-free, otherwise buy yourself some dark chocolate for back in your dorm room (or bring it with you to meals...)

Sorry, you're asking a question that's IMHO is not quantifiable. We can tell it's probably bad based on the ingredients (fried in a commercial environment, and hey, it's a college cafeteria). But we can't tell you "once per day is fine, but three times will give you a heart attack at 40". There's just no way to define it that way. Way, way too many variables over a long term. There's plenty of people that have eaten a lot worse at college and survive into old age. Recommendation is to limit it, don't eat it every day, but don't stress out over it in the short term if you eat a little more.

That's a tough one, I agree with Andrew that onion rings should be avoided for the most part. The are breaded and almost definitely fried in an oil that is to be avoided as well.

I definitely understand the stress cravings, but you just need to power through and make good choices. Everyone is a little different, for me, sugar is the big thing to be avoided so I would make sure to avoid that until the point that the ice cream and brownies and such are too sweet for you. This may sound crazy, but it really works after a while. I tried a donut hole a couple weeks ago and it made me gag.

The other strategy is to keep some things at home so that you dont have to indulge at the cafeteria. Keep some dark chocolate, berries, heavy cream and such at home. That way when you get that craving, you know you can treat yourself and not indulge there.

By 'mandatory' do you mean that the meals are included as part of your tuition or room/board? If not, I would seriously consider other alternatives.

Otherwise, I'm with Dragonfly. Avoid gluten and industrial seed oils as often as you can.

Honestly, I don't think it's that serious. Just have a cheat day where you can indulge (not too much) a little bit. If you know your caloric count for your body/weight then don't go over that by a lot. If you're working out a lot anyways most of it will be burned. It's hard to just continue to fight yourself and say no, but if you allow yourself a little bit of what you really love it shouldn't be a problem. It's almost like the carrot stick method in the sense that now you know you can pig out a little on friday or saturday beause you earned it through health eating choices and working out through the rest of the week.

is there a kitchen in your dorm? could you satisfy that onion ring craving by making some? slice onions, dip them in egg, then dip them in almond meal, fry them in lard. make some homemade mayo and enjoy them so much that the next time you see someone eating those sicko rings in the dining hall you'll remember the real deal and not even want the alternative.

Cafeteria onion rings? Yeah, stay far away. Onions caked with a gluten free (gum/nut free) batter and deep fried in tallow? Assuming you don't have a reason to go low carb jihad, my alarm bells just aren't ringing.

Hard to beat a homemade onion ring. If they're good and tasty, why not? Sure there's a little gluten (definitely sounds like you are NOT gluten-sensitive), who cares... PUFAs in the fry oil? Sure there's a little, but good fried food isn't dripping with oil. A little PUFA, while not optimal, isn't going to kill you short-term and there's a lot of other factors that'll determine long-term effects on health.