Anything you purchase through your personal iTunes account (music, videos, apps, ebooks, etc.) lives in your iTunes account, your iPad is just a device to access whatever you purchase through your iTunes account. Items that you purchase remain your property and you will be able to access them through your iTunes account even after your iPad is returned to the college.
The apps and media you download in iTunes can also be loaded onto multiple devices at once: for example, you can download songs from your iTunes onto an iPod, you can download apps onto an iPad, etc. – the songs or apps stay in your iTunes and you can continue to access them on your computer even after you download them to another device.