OK. I would say you probably have no bot registrations and are looking at about 100% human spam registrations right now, most likely Chinese or Russians. The Mac question might help in this respect as I doubt they are to know the answer.
Yeah, but it depends how determined they are... it doesn't take much effort to look up something on Wikipedia, etc. The situation isn't dire now, since it's easy enough to handle to odd spam message manually, so I'm not too worried about changing things at the moment.