A captcha is supposed to be hard for computers but relatively easy for humans.
"What archetype's icon is this?" is easy for anyone who's played the game. For someone who's new to the community, it may be difficult. I don't want to assume that everybody who registers is already familiar with the game. It's entirely possible people might recruit friends to play on Paragon Chat who never had played the game. If they can't answer the captcha, they might decide it's not worth the effort.
"What bonus do you get from slotting <whatever>?" is going to be hard for just about everybody to answer. Few people have set bonuses memorized. Even among people who played the game actively, there are going to be plenty of people who won't know where to find the answer to that on their own. For people who have never played the game, they might not even know what the question means, much less where to find the answer.
So while I appreciate those suggestions, I'm afraid I probably won't be using them. And I'd advise against using them on your own sites as well, unless you're very certain that everybody registering can easily answer the question--or unless you don't care if you deter real people from registering.
