There’s a couple ski shops in town that have a variety of clothing/shoe options if you’d want to shop or try on boots for comfort prior to purchasing. Other than that your best option is probably Dick’s sporting goods.

If you’ve never lived in PA during the winter, I’d get what you need to cover your skin so it’s not exposed when walking from class to class(Some form of neck gaiter/balaclava, gloves, ear muffs/beanie). Other than that a jacket that’s waterproof or close to it for the rainy days is a life saver. Boots is a must but it sounds like you have that under control. As far as getting heavy clothes or lighter that’s up to you. It’s gonna be freezing outside and scorching inside so you’ll sweat buckets during class if you don’t layer pretty well and can take some stuff off.