Good post, ProfPotter. Until you pointed it out, I didn't notice how the landscape surrounding Kandor was so vast. I also forgot that the first Kandor story had them create their own sun. That would jibe with my speculation earlier on this thread that they would create an artificial sun like their real one, Rao. (BTW, the definition of a city is a large community that doesn't produce most of its own food. We know Kandor seemed to need outside air supplied. It wouldn't be technically a city if they produced their own food, so Kandor must have involved not only the city proper but a fair-sized chunk of surrounding area -- which is exactly what your link shows us.)
An interesting aspect that Byrne got right was his ancient Kandor had a population of 40 million when it was destroyed 100,000 years ago. Even ancient Kandor was larger than our modern NYC (pop.: 8 million). That would suggest that a modern Kandor might have a population at least in the hundreds of millions in much the same way as 31st century Metropolis spans the entire Eastern seaboard. IMHO, one reason Superboy enjoyed visiting the Legion so much was visiting that era was an ersatz way of being on Krypton again as Metropolis and the tech approximated a Kryptonian city.
kryptonians (& daxamites) seem to adapt to any "gravity" when under a red sun.
That was made-up by the authors of the DC Who's Who and isn't really canon material.
Action Comics #500 had Luthor weaken Superman with an artificial red sun projector so he still had his gravity-based powers instead of becoming instantly a normal man. It wasn't until Luthor trapped Superman in a cell that duplicated Krypton's high-G that Superman's powers were fully nullified.
The actual books always outweigh the so-called 'official' DC Who's Who.