Interesting idea but for the first one, what would stop people from programming bots to know the answers in advance? The second one would still require a lot of work with the sheer amount of posts and new registrations. The subject of spam and newbies is definitely a hard subject to solve. Maybe until we adopt something like biometric logins (could cut down on bots and duplicate accounts) in the mainstream but I'm sure someone will find a way around that too.