Tetenal Vario Fix

I'm interested buying Tetenal Vario Fixer (Sodium Thiosulfite without hardener) which comes in powder form and has some questions:

1. Should it be diluted further than the stock solution, which is 5 liters pr bag, before use?
2. How friendly is the fume from this fixer? I normally find Sodium Thiosulfite fixers to be fine.
3. Does it take Selenium toning better than Kodak Fixer (powder with hardener) since the Vario fixer is without hardener?

Thanks

I found the answer for Q1:
the 5 liters are working solution, no further dilution. For express fixing mix only 3.5 liter instead of 5 liters.