Generally when you eat out (and the dining halls definitely fall in that category), it's not terribly healthy. If you go grilled chicken, rice and salad, you should be good. Limit the sauces you use to a few tablespoons worth. It will be more calories, but it will keep you sane. Grilled chicken, rice and salad day after day becomes extremely monotonous. No sauces is definitely worth a shot, you'll get the best results, but it will be more difficult. I'd also say fitting all of your food INCLUDING the salad on one plate is critical. Alternatively, consider getting a food scale and measuring out your portions. You will be able to track your intake much more exactly with MyFitnessPal (indispensable tool). Might get some odd looks, but fuck em.
I wouldn't call the Mongolian grill terribly healthy, you're basically getting stirfry and the oil can get ya. Even if you don't get any sauces (but they will ask you every time and it becomes tempting).
Now, as for calories. 1500 is a good starting point... For someone whose maintenance intake (amount of calories require to maintain your current weight) is in the vicinity of 2000-2300 calories. Your maintenance level is going to be significantly higher than that as you are overweight (you can determine it by following a link posted in this thread, check out TDEE and how to calculate it). As a result, I would recommend eating at 2000-2500 calories at first. Itll ease you into eating less. Losing a pound is roughly equivalent to 3500 calories (a statistic I've heard several times). If you eat 700 calories under your maintenance every day, you will lose a pound in 5 days (roughly. Everyone is different).
Finally, I would recommend that you hold off on exercise until you get the diet down pat. Eating right alone will drop you down fairly quickly. There's a saying I like that goes 'Abs are made in the kitchen'. You will find it a lot easier to lose weight if you don't eat enough to support it, rather than trying to work it off. Also, you may feel substantially more tired if you start working out and eating less at the same time. Since you're starting at college and you need all the energy you can get to make sure you get off to a good start, I'd say stick to the diet and wait for exercise. Maybe wait until midterms are over so you've settled in, had awhile to get accustomed to the diet, and gone through a high stress period (often when diets are abandoned). You've got plenty of time, and you don't want to mess up your goals by rushing.
I hope this wasn't too long or lecture-y! I can get a little long-winded at times haha. Best of luck!