Yes , you can surely do gargles with luke warm salt water . Just don’t ingest it else you will increase your salt intake. About mouth wash I can not say or comment ( it might be not discolouring your teeth as they might claim ) . You can use it for your satisfaction but do remember nothing can beat brushing . Brushing is the only most effective way to prevent any bio layer formation over your teeth also it stimulates gums (soft bristles with gentle manoeuver ) by gently messaging over them . About tooth paste .. it depend on which suits you the best and for that you will have to try yourself just don’t go with specialised tooth pastes .