Why you have all the first time visits but you find that you have short visiting times for your site? Check it out in this post and comment on it: 5 Ways To Make First Time Visitors Comfortable
Nice article - I've left a comment - not something that I've actually thought about before but I'm glad to say that I'm doing most of the things you mention.
Generally when I click into a thread I am prepared to read something, and hopefully something worthy of being read. When I get into one and see a "look what I wrote + LINK" I generally click the back button while muttering something about the price of good Spam in China. On the other hand, when I see a taste of the article, or something that prompts discussion I'll skim through the thread to get the general feel of things, then open up the link with interest, and if I like it come back to the thread and discuss. You see, I am kind of like a fish. I need something on the hook in order to bite, and threads like this are little more then a hook and line, which send many people off to look for worms in other places. Today I actually took the time to use the quick reply feature...but still did not bother with the link.
I have not read the article, but can think of a good few straight off. 1. have a fast loading site 2. don't overdue your ads 3. don't overdue your content so that it's hard to find the information they are looking for 4. have a nicely designed and warm feeling site that is easy to use 5. Make sure they know what your site is about from having a quick glance at it. 6. etc...