1, 2, 3 and 8 are harmful to the community. There should be some sort of reward for deep conversations, commenting on unpopular stories (which would then promote them) and not simply replying to a highly rated comment so it will be "above the fold".

None of this is rocket science, so I don't fault tptaceck but I hope most of this advice is not taken (except for 6+7).

I always thought Digg needed a new category called "Stories that get no respect" which are picked by editors or highly rated members as quality stories and put on a special page to promote going deep on HN.