What node identifies the instance parameters?
Not sure what you mean by this, but Element.Parameters will get all parameters and associated values for the element. If it’s an instance you’ll get instance parameters. if it’s a type you’ll get the type parameters.
@jacob.small same question, but can I get all the instance parameters existing Revit without asking from the elements or element types?
I don’t see why you would want this, as document A could use a parameter as an instance and document B could use it as a type, as the element (instance or type) determines if the parameter is an instance or type parameter…
This post on the building coder should point you to what you need: The Building Coder: Determining Whether Parameter is Type or Instance Bound
Is possible to get a list of parameter IDs and know if they are type or instance or can those with same ID be either on parameter instance or parameter type?
Possible - see the link. I do not believe that in the same project they can be both, but I haven’t tested. The OOTB width parameter for windows might be the best place to try that.
Shared parameters could absolutely be both type and instance depending on how they are associated with individual families. Also, knowing whether a parameter is instance or type based doesn’t really make any difference as it would depend on the element. And at that point you’d have to know which elements use the parameter and whether they use it as an instance or type parameter.
In a general sense, I can’t see how any of this would ever be that helpful. Is there something very specific that you’re trying to accomplish?