revausr

You should go with the USB 3.0 option. In my opinion USB 2.0 is always out of the question.

For college students Macbook air is more than enough. It is also a eye-turner and a conversation starter. But if you would like to do something more than just a regular college based work(Like gaming and any other flamboyant stuffs) I would recommend the the PC. Plus with your budget getting a PC is a more viable choice.

The HP is a good choice for me. Because you already have a MB air. Means that you don't need the smaller one. Use it for a general storage or something like the MB air cannot do.

I use this on my Clevo p150EM Amazon.com: IC Diamond 24 Carat 4.8 Gram Thermal Compound: Computers & Accessories. Am I doing it right? (I mean if it is the best thermal paste for my Laptop).

I use a Cooler Master Notepal U3+ on my Clevo p150EM. It works if you directly place the cooler fans directly on the laptop fan. The after effect is a dusty system. So I recommend cleaning the system every 3-4 months. In my system, the temp decreases of up to 20c.