There are several airports in the vicinity with reasonable access to Trier.
Trains leave hourly from Trier to Saarbrücken, Koblenz and Cologne. Timetable and ticket information could found at 
Trier is connected by the European motorway E44 from Luxembourg city (~50 km) via Trier to Koblenz (~100 km), E422 from Trier to Saarbrücken (~100 km).
Trier is connected to the Autobahn A6. This city is about one hour from Kaiserslautern or two hours from Mannheim.
There are some cruise trips from Koblenz to Trier. However: they are expensive.
Walking is the best way to travel around the city, though a vehicle is good when visiting the amphitheatre. Also there is a scenic overview up the hill by the amphitheatre where you can see the entire city. The city tours take you up there.
Trier is rich in ruins from the Roman Empire (protected by UNESCO), such as the
The Fachhochschule is in sight of the city. The first buildings were built in 1944 and were used by the Nazis to educate the next generation of soldiers. After the war, the complex was not officially used as a school. In the 1970's the university of Trier was re-opened and used the buildings, until a new university complex was built on the other side of the Mosel valley. Since then the Fachhochschule is using the complex.
Inexpensive and tasty meals such as pizza (with your choice of toppings), casseroles, salads etc. can be found in the formerly student-owned Astarix next to the theater, in the south-west of the inner city.
There are many Kebab stores, located all over the city. The best you will find in the Judengasse, the Ke-Pasta.
There is a McDonalds and a SubWay in the market square and a Burger King near the main station.
When visiting on a Tuesday be sure to check out New Mintons, it's minutes away from the main square and on Tuesdays they have schnitzelabend where you can order any schnitzel with fries and salad for just 5 euros between 6 and 10pm.
You can find delicious traditional German food (think loads of sausage, potatoes, cheese and beer) all baked in ceramic pots that come delivered to your table at the Kartoffelkiste (Potato House). This restaurant is always packed, very reasonably priced and directly off the city-centre.
Oechsle Wein- und Fischhaus, Palaststraße, Trier, Germany. Seafood restaurant with a wide range of wine collection, located at the city center. 8 euro for 3 oysters with a glass of sparkling Riesling.
Apart from the standard wines - Trier is in a wine-growing area - and beers (Trier - Löwenbräu, Cologne - often Gaffel Kölsch, Bitburg - Bitburger), one should definitely try Viez or Viez/Limo. Viez is an apple wine, which is often served with a splash of lemonade. But be careful: there is sweet and sour Viez don't order a big glass, if you are only testing.
Trier is a relatively safe city. Standard travel safety applies