A point on no.17 - Martin Belam's research suggests that those 'share this' widgets have no effect on bookmarking (http://www.currybet.net/cbet_blog/2008/09/socia...) - it would make sense. I bookmark, but I only ever use those widgets when on my mobile. On a PC I use the bookmarklet isntead.
I always find it interesting that paulbradshaw.co.uk comes top for searches on my name despite onlinejournalismblog.com being linked with my name far, far more often. Demonstrates just how important the URL is, even compared to links. But clearly content matters too - paulbradshaw.com is nowhere on those results as it hasn't been updated in years.