Perhaps start with the genealogy surname forums:
http://genforum.genealogy.com/kunkle/
The name von Gramatski probably came from Prussia (wild guess), and probably eastern Prussia at that; my most recent German ancestors came from a town which is now in Poland as a consequence of the post-WWII redrawing of borders by the USSR. Poland was basically knocked eastward into former eastern Germany, with the USSR getting a chunk of former eastern Poland.
For the German stuff, find someone who is fluent in German, probably preferable to get an actual German from Germany. As will Euro-countries in general, Germany standardized its language (using the public schools), probably early in the 20th century. There is some German language stuff among my family’s heirlooms, including (worthless) investment certificates and a colloquial German Bible.
Actually Prussia is a very accurate guess. That family owned a thousand acres in what was then East Prussia. They had potato contracts with the army during the Franco/Prussian war in the early 1870’s. Potato blight hit and they had to sell land to buy potatos on the inflated market to meet their contracts. At the end of the war they were down to 20 acres and the buildings. My great or great great grandfather dropped the title von from their name and took a job as a court secretary. William Shirer, I think, in his book on Hitler’s Germany refers to “the impoverished Prussian nobility.” Some relative back then was burgomeister (mayor) of Konigsberg. The area is now called Kaliningrad.
I have a lot of letters written in German sent to my mother by German relatives before and after WWII. The geneology is typed, so should not be too difficult for a German to read.