A PI Point can be referenced with one or more AF Attributes but it is also valid that a PI Point is not referenced at all. To answer the first part of your question, there's no way to do this except looking at all AF Attributes and to build a list of those referencing the PI Point of interest.
To see what PI Point an AF Attribute references, you need to first see if it is referencing a PI Point at all or if it might be using another Data Reference. The DataReferencePlugIn property must have a value of "PI Point". You will then find the path to the PI Point within the ConfigString property.