Is it possible to have a modal or toast appear on a list view when the case status or owner change? Or have them appear on their home page when they log in?

While creating a contact from Napili community I am not able to assign account to this new contact.
When I checked the debug logs I found that I am getting this error 'portal users cannot own partner accounts'.

So can anyone help me how to resolve this error
How can I create a contact in community where account should always be the account of the community's user (who is creating the contact)
 

Is it possible to launch a flow when a certain field value is selected?
Here is my use case:

• If Contact is seleced as "Client Reference" (Yes/No picklist), then I would like a screen (Flow) with 5 fields launches.
• Once flow is finished the Contact Record is updated.  

The reason I need the flow to launch is because our Contact object has way too many fields and I am only allowed to the client reference section below the screen fold. Instead of making users scroll all the way down to the Client Reference section, i thought it would be nice to just launch the screen with questions and then update the record. 

Any suggestion will be greatly appreciated