As far as I can tell, domain and subtype only can have one filter. Domain will determine which subtype to show.
As for contingent value, you can have as many. For example, column A will determine column B, from there column B will determine column C and on and on. I personally don't like how contingent value has to be set up because more column means more value to setup.
I have tried to set up on our portal server with no success which I am assuming it is because it is a new system that it is not ready for online use.
I would also like to see AGOL/Portal support with ArcGIS Collector App.