Richard - I've been following your comments through this thread and understand your frustration at not being answered. To flat-out answer your question about the number of links needed to send a comment to moderation - it's simple- he"preloaded" the spam. What we found out was that he was repeatedly calling the wp-comment-post.php page directly, incrementing the post id each time.This 1) hit older posts, and 2) if there wasn't a post with that ID, as soon as there is, the comment appears. He already had them loaded before you started chaning your comment link settings. So, in a nutshell, that's how it happened.
It was in the above situation that let me to find the loop hole for which there is now a fix for. Unfortunatly it does NOT fix existing pre-loaded spam, it will only catch new incomming spam.
BTW: I got hit by texas hold'em and bad ass boy this weekend. Fortunatly, with all the stuff in place, it was minimal - only 4 posts got through, 3 were caught and put into moderation. Based on what I've seen here, it looks like I was able to survive by the skin of my teeth.
Oh, and as for what does he get for click-throughs - nothing. It's not click throughs spammers are after. It's google ranking. Google determines the rank for a web site based on the number of incomming links. So if you get a site that has a lot of incomming links from multiple sites, well, you must be importaint to link to, and so gets moved up the listing.
TG