The cooking pans and pots used in induction hobs is ferritic and ferritic also can be manufactured to be corrosion resistance like austentic stainless steel.

Stainless steel can rust. How easy or not depends on its grade. However, some China made grade 304 is also no good quality. Not realy 304 since who is verifying

In hot humid place like Malaysia, more easily rusting. Exposed to chloride like clorox, will definitely rust it. Stairs handrail if you do not want it to rust, make sure you rub your hand going up and down daily

The more you use your sink, less likely it will corrode

I think there is stainless steel cleaner out there sold. Internet usually recommend you to use baking soda and vinegar.

I think during renovation, if there is metal dust even from steel left on sink, it can corrode it ... called galvanic corrosion.

Even leaving salt on it will rust, since salt is chloride material just like sea water.