There's a rather large FAQ section devoted to Nazi Economics. Here's some highlights that I think best answer your question:

• To what extent was Nazi Germany's economic development form 1933 onward "unsustainable"? And what effect did it have, if any, on their decision to go to war when they did?

The top response in this thread from /u/Volksgrenadier talks more specifically about the period of Nazi Germany before World War II and gives a good overview of the big political and military effects of the Nazi's economic policies.

• Some people like to claim that Nazi Germany was far right when it came to social policies, but far left when it came to economics. In reality, how did Nazi Germany's economy run on the political spectrum?

The top response from /u/peripatos speaks more in-depth about interwar economic policies and addresses in particular how Germany dealt with the debts while drastically altering the economy.

• How Did Adolf Hitler have the economy to sustain the rearmament of German military in 1935 ?

The top response from /u/vonadler branches into the immediate lead-up to World War II with a focus on the war economy and currency that the Nazi's acquired as they conquered.

Specific questions are encouraged so that specialists here may help enlighten you.

I'd recommend reading Adam Tooze's 'Wages of Destruction'. It's very well researched and addresses all of your questions. It's a little revisionist and Tooze's loathing for Albert Speer (He calls for Speer's death) is unjustified but the facts and most of the analysis are on point.

The BBC have recently shown a programme hosted by Top Gear presenter James May who references the introduction of the VW Beetle and a scheme created for the average German citizen to put money weekly towards the eventual purchase of one of these cars. Said money helped fund the war machine though the people never received their Beetle.

http://www.bbc.co.uk/iplayer/episode/b0467lbp/james-mays-cars-of-the-people-episode-1