Connect (non-siemens) PLC to SIMATIC ET 200 via PROFINET

Hello,

I'm currently evaluating the possibility to connect a homemade Soft-PLC running on Windows with a SIMATIC ET200 using PROFINET. The attachement bellow describes the setup. 

My questions are :

Q1 : Is it possible to map and set-up the PROFINET connection between the two modules with STEP7 / TIA-Portal ? (even if the Soft-PLC is not Siemens Branded)

Q2 : Is there a documentation about the PROFINET communication bewteen a PLC and and ET 200.

I've discovered that Siemens are selling another version of the ET 200, the ET 200 SP Open controller.Windows 10 is running directly on the module. A Siemens Soft-PLC can be executed on it directly.

Q3 : Is there a way to replace the Siemens Soft-PLC with my PLC to control the ET200 ? If yes, how can it be done ?

Thanks for your answers