NPAPI Questions

These are questions that bsmedberg found while trying to implement remoting for pieces of the NPAPI. I'd like to have tests and docs for these once the answers are known:

NPN_GetURL and family have an optional target: does the behavior change if the target is null versus the empty string ""?

NPStream has a url field

Do streams receieve a NPP_Destroy message before the associated instance is killed with NPP_Destroy? What reason code is given?

Do url notifications receieve a NPP_URLNotify message before the associated instance is killed with NPP_Destroy? What reason code is given?