There is no need to exchange money in the U.S., you will get a better exchange rate in Germany. You can find automated teller machines almost everywhere. Talk to your bank, if you are not sure if your card is accepted overseas and they will tell you. American Express traveler checks are another safe way to travel without a lot of cash. However, you will end up paying again a handling fee.
All department stores accept credit cards, but restaurants less often.
This way, you also will be able to call your parents when we travel, because they will have a hard time getting hold of you. Do not forget - it is seven hours later in Germany than in Dallas. You must have health insurance while you travel abroad. Make sure that you are covered by your health insurance plan or get additional insurance. You are responsible to make these arrangements.