Short answers, pulled from the story.
Italy established its first foothold in Eritrea in 1869 when Giuseppe Sapeto made a deposit to Danakil chiefs at Assab Bay. The Italian government formally took possession from commercial owners in 1882.
The Battle of Adwa resulted in a disastrous defeat for Italian troops against forces led by Emperor Menelik II in 1896. This battle ended hopes of annexing Ethiopia for a time and stripped Ethiopia of sovereignty according to the Italian version of the Treaty of Wuchale.
A census taken in 1939 showed that 53,000 Italians lived in Asmara making up 54% of the total population. The total number of Italians across all of Eritrea reached 75,000 that year.
Eritrean Ascari were colonial troops considered the best by Italian Marshal Rodolfo Graziani and served as the main source of paid employment for indigenous males after World War I. Many supported Italian guerrilla warfare until September 1943 when the Italian armistice ended active combat operations.
The Eritrean Railway reached Saati in 1888 according to engineer Emilio Olivieri's report. It finally arrived in Asmara during the highlands in 1911.