Marcio, don't bother with lawyers for now. Just get in touch with some other German photographers that shoot models and they'll likely can point you to a simple but adequate model release in German. I shoot models and always have them sign a release. It doesn't cost anything and it may avoid trouble in the future. I've also done a workshop in Berlin and the release that was used there was basically a German version of what I use here in Canada in English without any difficult legal language. It basically stated the full names and date of birth of the photographer (me) and the model, that the model was compensated (paid) for her service and that the photographer has the copyright of the pictures. In this particular case it also stated that the pictures could not be used for commercial purposes. Dated and signed by both.
Model-Kartei is a big German model photo site. Here you can easily search for photographers in your area that speak English and/or Italian.
Got to http://www.model-kartei.de/sedcards/fotograf/suchen/
Select Land: Deutschland and Ort: Freiburg
scroll down a bit and click on the tab "Gesprochene Sprachen" and click on Englisch and/or Italienisch.
There's 2 photographers in Freiburg that claim to speak Italian and 82 that speak English. Don't expect them to be all fluent though.
But you definitely need to learn German.