In regards to the DFG funding it says that foreigners are allowed "provided they have been resident in Germany for several years and have completed at least three years of scientific work as a doctoral or postdoctoral researcher in the German research system".

And from my understanding that is what replacement 457 will ensure.

"A DECRA Recipient may be awarded ARC funding of up to $139,369 per year of funding. The per annum salary contribution from the ARC is fixed at $99,369 (2016$), including 30 per cent on-costs, and up to a maximum of $40,000 project costs." - From ARC funding rules for DECRA.

So basically, close to $100K per annum goes to you (pre-tax) for 3 years and $30K to the university per annum. For project costs it depends on how you spend them.