Parts of Germany were occupied (Ruhr, Rhineland), other parts were simply taken from Germany, Austria-Hungary, and post-Tsarist Russia (to re-create Poland).
The “stab in the back” was credible to many Germans because they rarely lost battles; even the armistice was signed while Germany occupied its enemies’ land. The “stab in the back” was primarily laid at the feet of leftist agitators destroying the war industries at home with strikes (depriving the soldiers of needed munitions); the signers of the armistice were simply the last step.
Yes, but the country was largely unoccupied, and financial reparations were linked to ability to pay. Much, much less harsh than the impositions enforced on the losers of either the Franco-Prussian War or, of course, the Second World War.
Relatively speaking, the Versailles Treaty was not the overly harsh document that so many believe it to have been. It was certainly used to whip up anti-Versailles sentiment - a wave on which to ride to power by the Nazis.
There actually were those who believed that Germany ‘didn’t really lose’ the Great War. The ‘stab in the back’ myth was used by them too. Dan Snow has written and lectured on this. It’s interesting to look at things from a different angle.