To link your parents file to myCIC account, you will use your parents account. For sponsor updates, only ECAS is the source. But for your parents file you can check application status via ECAS and myCIC account after linking.
And for processing of applications, this year they will process atleast 20k applications as compared to last years 10k applications in first round so processing might take little longer than the previous years. Each case is different so you can't say that all cases should be processed at same time.