That's interesting. Can you elaborate, what did you buy that was a problem? and where (what seller) from?
It's easy to stay legal, but I believe some materials, although not epp restricted are 'watched' - not certain about that though.
As they are not illegal I imagine as long as you have a legitimate legal use in mind, there shouldn't be a problem.
What was the outcome of the knock?
Re your other question, I don't think anyone is actively running the society so probably not possible to 'join'
Good to have a bit of forum chatter though.
Good luck.
PS. I was going to PM this, but I believe many forum members will be interested so as not to do anything to fall foul of the enforcers.