For the pictures - Ive done it both ways - renaming pics and having them in a different directory - although it takes a little more space - does seem to help (especially if you name them in a theme with the name of the site) and changing the alt text.
I think that some of us have watched referrals closely enough to work out a "percentage gain" ratio for LLs to give us the ability to have a submit list whittled down by niche to no more than about 16 - it does take a while and for the larger LL owners that I know that use this approach - their submit lists are all different dependant on their selling abilities and what they are comfortable with for a work - to - return ratio
