Short answers, pulled from the story.
The German colonial empire began in 1884 when Otto von Bismarck shifted from opposition to state-sponsored colonization. The empire ended definitively by 1920 after World War I, with colonies transferred as League of Nations mandates under Article 22 of the Treaty of Versailles.
A private group founded the Society for the Protection of German Immigrants to Texas in 1839. This organization attempted to establish a colony called New Germany but failed completely due to constant lack of supplies and land.
Lieutenant-general Lothar von Trotha defeated Herero forces at the Battle of Waterberg in August 1904 and issued an extermination order. By 1908, around half of the estimated 50,000 Herero population had died, while the Nama suffered 10,000 deaths representing about half their population.
Germany acquired protectorates including South West Africa, East Africa, Cameroon, and Togoland by 1885. The northeastern section of New Guinea was named Kaiser-Wilhelmsland, and Adolf Lüderitz's trading post became known as German South West Africa.
In late July 1914, Britain and its allies moved against German colonies once war was declared. Japan seized island colonies including the Mariana, Caroline, and Marshall Islands, while other territories fell to Allied forces throughout 1914 and 1915.