there needs to be a rule change for pawn promotion
Pawn can be promoted to a queen, bishop, rook, or knight. Doesn't matter how many of those pieces of the same color are on the board. A lot of the time, a queen is the more desirable promotion.
There was, actually, a rule change for pawn promotion recently passed in Estonia: a pawn left at last row when pressing the clock now becomes queen.
In Indian chess, isn´t there a common rule that a pawn reaching final row is promoted to the piece of that position, except king, in which case the pawn also becomes queen?
The pawn is promoted to a higher rank and becomes a new piece that had no relevence to the game before. This said pieces captured have no relevence.
Would you also only be allowed to promote to a Bishop if the queening square is of the same colour as the one you lost rather than the one you still have?
There was, actually, a rule change for pawn promotion recently passed in Estonia: a pawn left at last row when pressing the clock now becomes queen.
In Indian chess, isn´t there a common rule that a pawn reaching final row is promoted to the piece of that position, except king, in which case the pawn also becomes queen?
Yes, that is the FIDE rule now. If you put a pawn on the 8th rank, don't promote it an hit the clock, then the move is considered illegal and the pawn is replaced by a queen.
I don't know about current variations but there are historical variations where the rules of promotion are much different. I have an interesting book of historical and regional variations that include some of those.
I've seen 2 queens VS 2 queens before...