Please find the answers inline
Do you evaluate the model that participant use ?
Yes, however we evaluate the overall solution i.e. usage of StreamAnalytix operator, analytics model used, pipeline design etc, for model evaluation we will have certain parameters that we will use.
Do we must explain why choosing the model, and the parameters used ? ( for example: if I use K-mean, do I have to explain why choose k , threshold values ?
Yes, you can explain the same on the submission page.