Comments:
#1. This already exists. Go to the foreign advisor, click the trades tab on the right, and then click a Civ you want info about.
#9. Would be very nice - though cities do this
after they have starved and regrown... ie a city that can use that square grows and grabs it... though not necessarily the city that lost that square... most annoying.
#12. CivII's Diplomacy
interface was better this way... you could move it off to the side of the screen during negotiations and actually do something else (fight, edit cities, look around, etc - anything you could normally do) while waiting for the other person or deciding what you wanted to do.
#12½. The Chat interface should do the same thing (a la CivII)
Good suggestions in general, but its late and I can't think too much more