Students from the European Union, Iceland, Liechtenstein, Norway and Switzerland enjoy unrestricted access to the German labour market. International students from other countries are allowed to work 120 full days or 240 half days per year.
The Career Service of Trier University and the "Agentur für Arbeit" provide an online database for student jobs. Jobs offers can also be found on the website of the "Bundesagentur für Arbeit": https://jobboerse.arbeitsagentur.de.
Additionally, some temporary student jobs can be found on the university's bulletin boards. However, many job offers will require at least some knowledge of German.
Accommodation is available in student halls of residence through the Student Services Office (Studierendenwerk Trier: http://www.studiwerk.de) or on the private market (e.g. http://www.hunderttausend.de). Monthly housing costs are approx. 280 to 400 EUR (for a basic dorm room with a shared bathroom) and 450 to 650 EUR (for a single apartment on the private market).