Allow yourself plenty of time to get to the airport. You may have two standard sized suitcases plus a carry-on handbag of a size which must fit below your seat or in the overhead bins. Be conservative with your luggage. International regulations used to restrict luggage to 44 pounds per person. 44 pounds will be really more than you will need.
Students can use the post offices in town or coin operated public phones for brief messages.
You can buy them at any post office from DM 12.- up. It is easy to get access to an ATand T operator from any German phone. Remember, the card must be signed and issued by you. You will need a sweater or jacket or both. A collapsible umbrella is very handy.