You can get a Debit MasterCard(I have one with my bank, Chase). You can use it just like a credit card, obviously. It doesn't build credit though. But it will not ruin your credit either, just your checking account
As for paying for school, good! When you are out of school and you got loans out the ying yang is when you can really make or break yourself. Pay those loans on time! You can break them into managable chunks depending on your budget. So what if it takes you 10 years to pay them back, it only helps to build credit in the long run. I was able to move into a great new apartment because I have outstaning credit, all from paying my loans.
As for the cell phone, be careful...
You'll probably have to go with a cheapo month to month plan. If you want to get something like cingular their minimum plan is like 40 bux a month, plus you are signing a contract for at least 1 year I believe. Also, they will run a credit check on you! Since you probably have no credit they are going to hit you with a nice fat payment (I would expect over 200 easily) PLUS you have to buy the phone, which would be another 100 or so. Cell phones aren't cheap!
Good luck and remember to keep your head up.