Not a good idea unless........YOUR MAP IS IN SPACE! 
yeah well, i played around a bit with it, made a hill with watchtower, lots of torchers around it so that people would know the general idea where to run, as light of torchers is visible in those conditions ;] looked a little like scenery of "Aliens" hehe
but now i come back to other map and i once again tried that water_river object, and somehow it works correctly? i mean it doesnt give this effect after reloading a map(but my other map even after reloading gives this effect) so i dont know whats the deal with it, maybe its a glitch and not feature
The only way I know to copy an object is to right click. Not sure what else you are trying. Unfortunately, I don't think there is a way to group objects together and copy them as a whole. I made a wheat field by placing each plant. I almost went insane.
FYI, you can delete a ton of objects at once by shift-left clicking them in the object list, then hit delete. I had to delete a wheat field also. 
i was asking if its possible ;] anything close to grouping is selecting multiple objects while holding ctrl, god damn if you could just ctrl+c that it would save A LOT of time ;] but yeah im also putting each grass one click after another ;/
