Short answers, pulled from the story.
Ludwig Erhard officially introduced the Deutsche Mark on Sunday the 20th of June 1948. This reform replaced old Reichsmarks at a rate of one new mark for ten old marks and wiped out ninety percent of government and private debt.
The Council of European Union fixed the irrevocable exchange rate so that one Deutsche Mark equaled 1.95583 euros effective the 1st of January 1999. The currency ceased to be legal tender in Germany after the 1st of March 2002 when euro notes and coins were fully introduced.
Four series of German mark banknotes existed from 1948 to 2001 with denominations ranging up to one thousand marks. The fourth series launched in 1990 included advanced security features like windowed security threads and color shifting ink to counter forgery technology advances.
The Deutsche Mark served as the official currency of East Germany starting July 1990 before unification occurred on the 3rd of October 1990. East German marks exchanged for Deutsche Marks at a one to one rate for the first four thousand marks per citizen.
First Deutsche Mark coins appeared in 1948 and 1949 using bronze clad steel for one pfennig and two pfennig denominations while five pfennig and ten pfennig used brass clad steel. Cupronickel DM1 coins released in 1950 followed by cupronickel DM2 and silver DM5 in 1951 until silver replaced copper nickel in the DM5 coin in 1975.