get links from other high PR sites as well as posting in do follow forums, i am not sire if DP is a do follow forum, but i do not believe that it is, btw PR takes a long time usually.
very nice! it may be like that... as social networks have lots of traffic and PR6-7-8 on their homepages... it might be a good idea
I heard about it in another forum but I also work with Analytics and the data I am seeing really supports the suspicion. Whether it's true or not, engaging your visitors and growing your targeted traffic is always good, even if you don't see that green stuff.