How Captain America actually returned all the six infinity stones at the end of Avengers Endgame?

Did he return all stones in the same form and at same exact spot from which they were taken? How does two Captain Americas workout in the Main MCU timeline and where the heck did he get the Shield that he handed over to Falcon?

Who is the more powerful Avenger in the MCU? Is it Captain Marvel or is it Scarlet Witch? We have seen both of them do some incredible feats be it Scarlet Witch destroying an Infinity Stone or Captain Marvel tearing down an entire Kree fleet on her own.

So, who would in a head to head fight?