The other possibility is a netbook, like an Asus Eee PC, and portable DVD drive (which is quite small). This would cost you no more than an iPad and do what you want.
If your test review materials are on PDF, they can be imported to the Ipad via Itunes or Dropbox. There’s an excellent PDF app called “Goodreader” that I use all the time to read PDFs on my Ipad.
Apparently, you cannot connect a cd drive to an ipad. This from ehow:
Do you need to install media that is on a CD? If you need to install media that is on a CD, on a netbook you can simply connect a CD drive using a USB cable. The only way to get media from the Ipad is to purchase it from Itunes or applications store.