I'm pretty sure that the rules are indeed different for USA & Mexico based FB members. For them Gold is equal to Sky Team Elite, not Elite Plus. It is only Elite Plus which gives SkyTeam lounge access when flying in Y on any Skyteam carrier. US-based Gold gets you access to any KLM or Air France lounge when flying on any SkyTeam airline. Eg. departing Amsterdam on DL in Y you can still enter the KLM lounge, but departing JFK on DL to Amsterdam you will not get access to Delta's lounge.

Don't know about your first question, but I would guess that you are on the list after NW/KL platinum and non-US golds, but before silvers.