Student ID card

I encourage you to do a coupe of things: Find a copy of Europe Through the Backdoor and read it, go to the Lonely Planet and Boots n All websites and post your questions there as well. Buy a money belt. Use a Pac Safe bag. Your student ID, driver's license and Passport is more than enough ID for your travels. Make certain you have copies of each stored somewhere. My preferred method is a small flash drive.

I would actually look into getting the ISIC if you can. While your college ID will suffice for most things, I have been to a few places that only accept ISIC for their discounts. Granted, I live in Budapest now and have traveled primarily in Eastern/Central Europe, but I've seen this in a few places from France to Romania. Additionally, the card serves as pretty decent travel insurance while you're abroad. For $28 (I think) and the cost of a passport-sized photo, you can't beat that! I have a friend who hurt herself quite seriously and was able to easily make a successful claim with the agency. I know the cards were super easy to get at the university at home--just walked up, filled out the paperwork, and walked away with the card. (I worked with lots of college kids preparing to study abroad).

In my (admittedly dated) experience getting student discounts with foreign student ID tends to be far from certain, but everyone accepts the ISIC. It mainly depends on how many things you actually want to do which offer student discounts in the first place, and how much these discounts sum up.
Yes, it's a math exercise ;-) If you're fairly certain the discounts will be higher than the price of the ISIC, get one. If on the other hand you'll plan on few things which will offer student discounts, or you'll could live with the fact that your collage ID won't be accepted in every case, then I wouldn't bother.

Read the fine print on the ticket information for the places you actually plan to visit. While some will accept an ISIC for free/discounted admission, others will require proof that you are a student at an EU school and/or an EU citizen.

Here in Italy, most of the places that I have seen that offer a student discount do so for EU students under a certain age. If you are above the traditional age for college students you might want to keep that in mind also.

If your college has an Office of International Study/Study Abroad office, you should check there as you can probably get the ID through them. Or, what Jamie said!

Thank you for your help!