Shimano Chainring Compatability In my previous question we determined that I probably need new chainrings. I was/am planning on replacing the chainrings, and leaving the original crank. 

Now this bike is running Shimano 105 FC-5600 kit.  I refer to the Shimano drive-train compatibility chart here which says that that the FD-5600 front derailleur needs FC-5600,FC-5650,FC-R600 or FC-R550 front cranks. 

Since I have to replace it, I wouldn't mind upgrading to a Ultegra-level chain-ring. According to (my reading of the chart), this is not possible. (which seems strange, I would have thought any 130BCD chainring with the same screw type should work. Is there a problem with derailleur clearance or something?)

1) Is this correct?

2) If so, is there a compatibility chart with other brands? (FSA/SRAM - obviously Campy wouldn't work!)

Thanks in advance
The current Ultegra chain rings are in fact physically compatible with the 105. They do not look good on the 105 crank, however, because when Shimano redesigned the Ultegra and DuraAce level cranks to their Hollowtech II design, the made the chain rings hollow as well.
Th point where the chain ring meets the crank arm is noticeably thicker, and shaped quite different on the Ultegra chain ring and crank, compared to the 105.
This is the 105 FC-5700, which is newer than your FC-5600.

This is the Ultegra FC-6700, which compares to the FC-5700.

See the extra shape and thickness where the chain ring bolts are? That is why they do not list Ultegra rings as compatible with 105.
You can physically bolt them up, and they will work, but they look bad, and you don't get most of the benefits of the Ultegra ring, (mainly added stiffness), without the whole crank.
A set of Ultegra rings will cost 150 dollars, and a whole crankset, including rings will be around 250 dollars, so it might be worth just doing th whole crank, if you're interested n upgrade.
Otherwise, just stick with the 105.