I am german, and I may be able to answer many of the thoughts presented here. Trying to rank english sites on google.de will not work for almost any keyword thats worthwhile.
Getting good content will be difficult if you don't know any german. Google translate will not provide you with good articles. I've tried autoblogging translated articles, and results were not super bad, but not good either. (Got traffic, but visitor times of 3 seconds because they immediately figured out that the content has been poorly translated)
An idea however may be the following:
textbroker.de and content.de are german article writing portals. You can order articles there, rates starting at 0.015€ per word. (but at this rate articles won't be very good either, but much better than google translate)
You could write the order specifics in english, and google translate them. I think that should work.
For google.de, your backlink profile should consist 90% of german sites (with german content that means / look for lang="de-DE" and meta name="language" content="de"). .de domains are in favour, but .com, .net .org, .info, .ch and .at will work well.
Also consider that austria and parts of switzerland will also search german phrases. (Hence why it makes sense to also have links coming from .at and .ch)
Germans are very critical. If your content is crappy i.e. obvious spelling and grammar mistakes, they will leave. (Except maybe for a few young newbies, but they don't usually have the cash you're looking for)
To get backlinks, I suggest use blogs, forums, bookmarking sites and paid links. One specific widespread (not very popular, but also not too spammed) bookmarking platform is "public bookmark". It is possible to find bots that can post to it. You will easily find more popular bookmarking by researching yourself (Mr Wong etc.) RSS Aggregators will also work well.