Yes
Yes
Researching around this cause I thought it was interesting, certainly not an expert. Apparently your case is considered an “accidental American” and you can probably search for others in your scenario. The IRS has a tax treaty with Germany that should be able to help you reduce (or maybe eliminate) your tax burden.
https://www.linkedin.com/pulse/tax-implications-dual-citizenship-what-you-need-know-daniel-morris-jfxle https://www.irs.gov/businesses/international-businesses/united-states-income-tax-treaties-a-to-z
Learning Go for a new job.