One of the first things I'd do is to look at what your college recommends. If you have any hardware requirements (say, the ability to use autoCAD for a class) you're going to want to make sure that those are met.
I have two laptops, but the one I use for theatre is a Chromebook. I've found that it's all I need for theatre--internet, long battery life, and light weight. With the exception of Q Lab, all the programs I use have online equivalents--every thing I do is through the internet. It's certainly not an option for the technophobic (and I do a lot of things through the command line, which most people are not comfortable with), but my point is that you don't need fancy tech specs for stage management.
When you're looking at battery life, one thing to consider is the weight of your power cord. Some of them run close to a pound, meaning a fifth of your laptop's battery life. For college, I'd look to maximise battery life and minimise weight. I'd get something with a fairly small screen--the majority of school or work related things you'll be doing won't require much screen space--and then get an external monitor for your dorm room, and you can CAD or watch movies on that.
If you're looking at macs (or some pcs) you're going to be seeing a lot of hype about SSDs (if you haven't, it's a type of hard drive). These claim faster access speeds, but they really aren't worth their price. In the great majority of laptops, you're not going to notice the difference and they are significantly more expensive. SSDs are magically with things like ChromeOS (and kinda with the mac book air), but it's not worth the price with most of the laptops you'll be looking at.