When you conquer the lake/desert/forest you get the bonus it states. Your resources production will go up 29% (in your examples) if you beat all the defenders. You are allowed as many valleys as your level of town hall.
Originally Posted by Elmister
When you conquer it, your troops will stay at the location as eat 2x the food, you may see your food go into the red. You should recall them [don't abandon, recall] and you will be fine. Most people see someone taking their valleys as an act of war, so most people wont try to conquer someone else's valley.
Am I wrong? Then quote me and show me. It's how I learn. I don't really care about rep.