Question 1: Summer is always slower, not only in Germany
Question 2: A few years ago (ok, in the late 1990s), I did what you are trying to do, with a comparable level in German. Some companies were open in saying I wasn't good enough in German; others expressed interest due to my English and French skills. I ultimately got an offer in one of these (CSC Ploenzke, which was at the time the premier German-speaking IT consultancy, on par with with Accenture)
Bottom line: You aren't choosing the easiest path, and may need to find someone looking for a specific skill set that you offer - but it is definitely possible. I think German or Dutch companies (Northern Europe in general) are a lot more open to this scenario than French, Italian or Spanish ones (Southern Europe).