I think both salt and vinegar are bad for the soil/worms, boiling water probably would kill top-growth, but doubt it would kill the roots, as well, so perennial weeds will regrow.
Flame does kill top-growth - that's why you can buy gas weed wands but again it doesn't kill the roots, unless you bake the soil as well. Bricks anyone?
I don't know about soap, but we spray plants with washing up liquid diluted with water to kill aphids, rather than kill the plants
2 on the list work well, weeding and covering (with cardboard/weed control fabric) but we already knew about them
