I love how much thought you're putting into this! Reminds me of how I am with big decisions. Research until I turn blue, haha.
You've gotten a lot of good advice, but there's definitely some things I want to add, as someone who's relatively fresh out of college. DEFINITELY wait until you're in school before you get a dog. Evaluate honestly how much time your academics and social activities take, and how much you'd be willing to sacrifice to make room for a dog in your life. As much as I love Samwise? I wouldn't have done well with a dog in undergrad. I was way more involved in certain activities than I'd ever expected (which was awesome! I'd have hated to miss out on most of it), and classes can certainly kick your behind in ways you can't always predict. Senior year especially. In your case, I'd definitely lean towards getting an older dog. Puppies are tons of work, and I say that when we got ours a little older (12 weeks) and I had my fiancee, who was equally committed to helping out. You don't want to get a puppy, then realize the next semester that you're stuck with a schedule where you can't go home for 8+ hours. An older dog can hold it, and most are fine with napping during the part of the day you're not there. Is it doable with a puppy? Sure! But it's a lot harder. Something to think about.
As for breeds... while I agree that many large breeds make as good or better apartment dogs than small breeds, landlords in your area may not agree. Look into what kind of housing is readily available in your budget... and below your budget. Just in case. Some areas make it very hard to find apartments that allow dogs more than 15-20 lbs. In some areas many landlords ban certain breeds and mixes thereof. Some areas you can find housing, but the fees and 'pet rent' piled on top can put you over the top, expenses-wise. Even if you find one place that'll work, try to get a feel for whether you'll have options if you need to move for whatever reason. It's tempting to aim for the best place you can afford, but speaking as someone who did that... don't. Find somewhere that meets your needs, but you can also continue to save money. Super important, especially with a pet! We've got a member here whose Boston/Bulldog pup has racked up several thousand dollars worth of vet bills before he's turned two. You just never know, with dogs.
Just keep in mind. Things change. When we got Sam, I never expected that only a year later everything would be different - my fiancee back in her home country working, me waiting on a visa to live there, having to move back in with my parents because alone, I couldn't afford any housing that would also accept Samwise. I'm extremely lucky to have supportive parents, or I'd be in a lot worse shape. Haven't regretted getting him at all! But for a lot of people, early 20s is a rocky time, so you've got to be prepared to roll with the punches.
Sorry for all the rambling! For the breed question, I like the lab and aussie suggestions. If you do need to go smaller, beagles are great family dogs (can be loud, though), and this forum has really turned me onto rat terriers! Sporty little dogs, but not as stubborn as the 'terrier' usually implies. I'd plug poodles (come in all sizes, great personalities, generally up for anything you can throw at them activity-wise), but they of course do require some more intensive grooming.