Have a link to the Korean abrasive cloth you recommend? Would like to try it.

google this ... Crown Choice Heavy Duty Dish Scrubbers for Cleaning Dishes & Pots ... its a slightly abrasive cloth

How hot is the water? Soap kills and wash bacteria off the dish's surface, so if you substitute it with just hot water, the water have to be hot enough to kill those bacteria.

You'll be fine, bacterias are everywhere, you literally have poop particles on your toothbrush and everything else in your bathroom, you'll be fine

I live in a country where bacteria-borne disease is rampant (typhoid, tuberculosis), so not using soap to wash dish is a dangerous thing to do, unless no other people ever come to your house.

Fair enough, in non risky areas people tend to be too OCD about these things

What if they are greasy?