Short answers, pulled from the story.
The official formation of the Reichswehr took place on the 1st of January 1921 after Germany met the severe limitations imposed by the Treaty of Versailles. Personnel strength was limited to a professional army of 100,000 men plus a navy of 15,000 men.
The establishment of a general staff was strictly prohibited under Article 160 of the treaty while heavy weapons above defined calibres were banned. Armoured vehicles, submarines, large warships, and any type of air force were also forbidden for the Reichswehr.
In 1927 twenty percent of the officers were from the former nobility down from thirty percent in 1913. The homogeneity of the Reichswehr officer corps was greater than it had been during the Empire with ninety-six percent of officer candidates coming from upper social classes in 1926.
A secret Reichswehr aviation school and testing facility was established at Lipetsk where some 120 military pilots trained as the core of a future German Air Force. Tank specialists were trained at Kazan beginning in 1930 while chemical warfare agents were jointly tested and developed at the Tomka gas test site near Saratov.
On the 2nd of August 1934 the day Hindenburg died Reichswehr Minister Werner von Blomberg had the Reichswehr swear its oath personally to Hitler. On the 1st of March 1935 the Luftwaffe was established and on the 16th of March universal conscription was reintroduced both of which violated the Treaty of Versailles.