1/ Good idea
2/ Saving the population list would be so cool, I've asked about this and its not on the cards, at the moment. 10 - 15 hours each, either your insane, misguided or using a very old computer
Remember your population dose not have to go as far as you can see. Two or three populations using lower detail in the distance works better and quicker and there is no point at all in populating the back of a mountain you cant see!
3/ Only realy usefull if your using insane settings (like described above
) Longest populator runs I've ever had is about 15min, say 10 pops of 50,000 to 2mil for example
4/ Copy the area size and coordinates from the populator to the image map node (make sure its in top downy axis)
5/ Not really, just looking at the populator as it reaches 100% is as good as it gets for the time being
6/ Dont worry about it, there are errors but your final render should not show them
7/ Remove any spaces in your file path names, eg "My Documents" is not liked, nor is "my file.tgo" but "my_file.tgo" or "MyFile.tgo" is fine
Hope this helps, just my response, I'm nothing to do with Planetside. Sorry for being cheeky about the 10 -15 hours, I'm sure you have your reasons.
Good luck
Richard