I got that code working (redid it - took the original averaging code and just applied a multiplier).
I haven't managed to figure out the location thing, though.
I have added a column to display the added date (which I've renamed release date). Only issue there is you have to use PHPMYADMIN to edit the dates after they are added, but it's doable. The main reason I wanted to do that was so I could add upcoming products, but have them not show a review link until the release date. I can't for the life of me figure out how I compare today's date to that date in a bulletin template conditional, though. I suspect it's not possible.
Here's where I am so far. It looks quite good, I think, though the code and templates are probably now a hideous mess:
http://www.enworld.org/forum/productforums.php