Yea - he takes questions from all over and as for now he only took those of quite a little importance (though one was from me so I'm was quite hyped when I saw that - I know ... lame xP), so I wouldn't hold my breath that he will answer something HUGE. They want - for whatever reason - keep many things secret ...
Those are just questions that he has observed himself - he often lurks on the forums and whatever he sees to be a frequently discussed topic is what he considers a "burning question." So there's no official spot to submit questions, although an unofficial thread has cropped up here which might catch his attention: https://www.pantheonmmo.com/content/forums/topic/11244/questions-for-joppa