[ambition]

I say all of the following at risk of being wrong. Mentally prefix each sentence with "I'm not sure but".

The ranking system puts together the number of points a story receives and the recency.

Your karma is the total score of your submissions and comments. You get points when other users vote up your stuff, and lose them when they vote you down.

'Saved links' is the collection of stories you've voted up and you've submitted.

noprocrast enables maxvisit and minaway. These three parameters are anti-addiction self-protection: maxvisit limits the length of time you can use the site, minaway specifies how long you have to go away before resuming using it.

Gabriel Weinberg put together an awesome "best-of" FAQ: http://www.gabrielweinberg.com/startupswiki/Ask_YC_Archive

Hope this helps.