Thank you Babs and Min!
I was planning the end around 960C as earlier I went to a studio that offered firing service and they fired my pieces from the same clay, same thickness at this temperature (then glazed around 1100c) and they turned out fine. As far as I understood the German (I do speak a little), % relates to the time, as the example says: 4,5 hours with 30% makes it 1,5h.
And the lowest temperature I can set is 500C. I plan to buy cones and need to replace the ceramic cover of the thermometer rod (?) anyways, already contacted the company about that.