Is Dmart cheaper than amazon?

yes, without doubt. Amazon is cheaper only in mobiles and consumer goods. For everything else, it cheaper outside. If one is willing to search.

Yes

Yes, but If you have swiggy CC you can get some items on instamart cheaper than dmart

Yes

Not all products are cheaper on Dmart. I have seen some products cheaper on Amazon fresh. I have compared prices across star bazaar, Dmart, Reliance smart bazaar and Amazon fresh. Different products are cheaper on on different stores at different times.