I'm editing Sunset Valley in CAW, for the purpose of adding new lots and making them look right, and to avoid the routing issues caused by using the world editor. I want to keep all the original households, and am not planning to add new ones, or even move them to different houses. Is it necessary to annihilate the population and then add them all back in when I'm finished editing the world? I've read the tutorial on populating worlds, but I'd rather skip that step if it won't mess up my world to just leave the population intact as I edit.

You can leave them in the world as long as you don't move any occupied lots. If you need to move a populated lot, you can go into edit town, evict the household, then either delete them, or place them in another residential lot.

Thank you. I'm glad to know that.