Share 'Friends, Real and Otherwise'

For people not known to you personally (such as your cousin Mary Sue), whom should you allow to be a Friend, and why? Do some Friends use their access to your viewed films and queue to boost their ranking vis-a-vis yours? How? What are the criteria to use to drop Friends? And let's talk notes -- esp. those Copy All notes touting your latest review, or whatever? Is it better to be a Friend or a Fa…