Help required in choosing the city for long term stay

Hi,

I am an IT professional and moving to europe in Sept 2012 for a long term assignment with European Government, Luxembourg. I am looking for a rented accommodation in cities / towns at Luxembourg-germany border.
1. I am considering Trier and Konz right now. Which city is better in terms of cost of living, safety and connectivity to Lux.
2. Since I want to finalize the accommodation before i come there, I am just wondering, if i look for a real estate agent, how relaible they are? Can we rely on what they say and finalize the property just by looking at the pictures?
3. How much do the real estate agents charge as their fees? Most of the real estate propety sites mentions about 2.38 months rent. Is it the standard in Germany.
3. Are there any websites or any other medium where property owners directly post the advertisements for thier property?

Help would be appreciated.

Regards
DassKhands