Interesting, i know a lot of americans go to Berlin but German laws make being a freelancer quite tricky. Interesting to see it's easier in the Netherlands.
It was quite easy for me to get a German visa as a freiberufler. Basically I just needed health insurance and to show that I had past income as a freelancer. It's been renewed each year without a problem.
Akaik it's harder to get a fixed job because the company must prove there are no locals who could do the job. It's just more paper work for them.