Short answers, pulled from the story.
The Treaty of Craiova was signed on the 7th of September 1940 and ratified on the 13th of September 1940. Ratification on the Romanian side was carried out by Prime Minister and Conducator Ion Antonescu; King Michael I did not ratify it personally.
Romania ceded Southern Dobruja to Bulgaria under the Treaty of Craiova. The territory covered 7,142 square kilometers and had been under Romanian control since the Second Balkan War of 1913.
103,711 Romanians, Aromanians, and Megleno-Romanians were forced to leave Southern Dobruja for Northern Dobruja, while 62,278 Bulgarians moved in the opposite direction from the north to the south.
Romania agreed under the pressure of German diplomatic backing for Bulgaria and the threat of Axis arbitration. Adolf Hitler had expressed his wish on the 31st of July 1940 for Southern Dobruja to be returned to Bulgaria, and Romania, also trying to win Axis goodwill in its dispute with Hungary over Transylvania, announced readiness to cede the region on the 29th of August 1940.
No. Unlike virtually all other territorial settlements mediated by Nazi Germany, the Treaty of Craiova was not reversed by the Allies after World War II. Southern Dobruja remained part of Bulgaria.
The Dobrujan Germans, who lived in both the northern and southern parts of Dobruja, were transferred to Nazi Germany through the Heim ins Reich policy, which translates as "back home to the Reich."