It is advisable to rinse them off in warm water as Washing up liquid is a bye product of Oil & can be harmful if allowed to build up on your plates etc. Just wiping them only leaves smears of soap, when you think of an automatic dish washer you always gt a rinse cycle.
you don't have to, but i do because if i don't, my mug of tea usually tastes funny, so does the food off my plate. it's down to personal choice really.
Unles its organic dish soap yes u should rinse. soaps are hazardous and although it may not harm u it may harm someone else. ever put your finger in your mouth after washing dishes. Nasty taste. atleast rinse before using. Company may have a reaction you never know so be considerate. would'nt want to give someone a glass of water that taste like soap.... Also pick wisely when u chose to cut corners....