@1) In fact 4870 has even better solution, do it this way:
http://tiesie.gmxhome.de/GK/so%20nicht.jpg
Just DO NOT PUT THOSE FEW MEMORY HEATSINKS IN THAT HOLE LIKE ON THIS PICTURE! Just use the red plate, and nothing else. If you want, you can stick few more heatsinks on top of red plate to have more dissipation space, but I haven't tested it so don't know if it would help.
@2) ofcourse heatsink is not enough, you have tu have AIR running over it :D So just add your HR-03 once you put this red plate, and than stick a 120mm fan on top of it si it pushes some air over the rear of the red plate if possible - like this
http://tiesie.gmxhome.de/GK/GKAC12cm.jpg
Since HR-03 is smaller than S1 (on picture), and is mostly over GPU socket, the fan probably won't be pushing a lot of air over VRM part in the rear, so you can maybe add one more 120mm fan just over where VRMs are like you've said you did in the later posts.
And that's it!