Well first thing, you don't know how many votes Kerry had in Phila. You know how many more votes Kerry had than Bush. I think that addresses your entire complaint. Thanks.
Wrong again. The map shows how many votes Kerry had, not his percentage or even the number of votes over Kerry had over Bush. The map just shows raw votes, which does tell me much more than cities have a lot of voters and Kerry voters tend to live in cities. It is not a particularly useful map.
No - it doesn show the number of votes Kerry had over Bush (the margin). Otherwise you
would be able to notice there's a big city called San Diego.