Personally, I only hit the Newest nodes, but if I have replied to a thread, I often go back to it direct, as you only get notified of replies to your own comment.

.oO(Which makes me wonder if you can subscribe to a thread, like in vBulletin Board.)

A synopsis would be good, but I think readmore tags should always be used to hide content.

As far as cutting a post short, people have difficulty in making a post make sense, let alone cutting one in half. I think this would just add to some of the poorly formatted questions etc.

My 2p.