Short answers, pulled from the story.
The Regency Council in Warsaw announced its intention to restore Polish independence on the 7th of October 1918. Józef Piłsudski returned to Warsaw by train on the 10th of November 1918 after spending sixteen months in a German prison in Magdeburg.
Poland solidified its independence through a series of border wars including the Polish-Soviet War which ended with a decisive victory in August 1920. Other conflicts included the Polish-Ukrainian War that broke out in Lwów on the 1st of November 1918 and the Greater Poland Uprising from 1918 to 1919.
The Second Polish Republic operated as a parliamentary democracy from 1919 until May 1926 when Marshal Piłsudski led an intentionally modest life and took power through a military coup. His regime was called Sanacja meaning healing or sanitation and he died just after an authoritarian constitution was approved in spring 1935.
Prime Minister Władysław Grabski introduced the złoty in 1924 to control massive hyperinflation without foreign loans. This currency replaced five different currencies that existed within borders before his reform and helped achieve average annual growth of 5.24 percent between 1920 and 1929.
The census of 1921 showed thirty point eight percent of the population consisted of ethnic minorities while sixty-nine percent identified as Polish. Fourteen percent were Ukrainian and ten percent Jewish with three percent Belarusian and two percent German completing the demographic picture.
The German invasion began on the 1st of September 1939 ending sovereign rule for the Second Republic. Warsaw fell to Nazis on the 28th of September following a twenty-day siege and open organized resistance ended on the 6th of October 1939 after the Battle of Kock.