Yes you still get notifications when using your wifi. It doesn't save battery, it helps add to the draining of it like anything else would. The best way to go back and forth is using the toggle switches. You can add them like any other widget. Long press screen or click the plus, then go to widgets. you can use either power control wich is a stock android widget, or you can go to settings and add a toggle switch for each thing(mobile data, wifi, airplane mode, brightness, etc.) I personnaly prefer the toggles, they look a little cooler to me.