Some good points in your dissertation, Thanny. One thing to keep in mind is that it is NOT necessarily the tubing size or AMOUNT of coolant...it is coolant flow. A slow moving coolant through a large tubing diameter will not be as efficient as a smaller diameter with a more powerful pump. As you noted, correct radiator and fan selection would be paramount in a well designed system.
flash67, There are many components and explanations of their virtues found on Frozen CPU's site as ONE example. One can determine the pluses of different radiators, but integral reservoirs will make the build simpler and less cluttered.
Overclock3D, Swiftech, EK and many other sites have contributed to advances in computer component cooling. Pays to educate yourself from many sources before making substantial purchases. One often overlooked consideration will be future maintenance of your system and the correct procedures in filling, refilling, draining and flushing of the coolant and keeping the loop free of mundane things like algae. Think twice before using coolant dyes. Obviously, whatever you buy, there must be no potential for leaks...they could be catastrophic! Read up and enjoy your project...am thrilled for you!