I wouldn't leave dogs out in a yard all day in the city. too many potentia issues/dangers (from barking and annoying neighbours all day, getting out, people throwing stuff in, and yes destruction). anyway you can start crate training or training them to spend time indoors when you are away?
ETA: the rest is training. you need to be outside with them to redirect and possibly with time they won't be destructive. but if you are not there they will do as they please and practice the behaviour you don't want.
Potty area - just keep them on leash adn bring them there to potty (a long line may work too). it's a pain in the butt at first but otherwise it'll be impossible to ensure they only pee in the one area.