Thank you! I am aware of the issues
1) I will probably not make an option to add whole folders because a folder can contain mixed types of objects. Instead I will probably add an option to use Shift to select a large number of objects (like when you select files in Windows)
2)Yes, I know its a problem. I will add an option to remove the last element.
(3) modifying population density is difficult to do in an accurate way. I could add a country-wide modifier, but it is probably too coarse.
Thanks for the compliment and thanks for complaining! It helps A LOT!