Edit: Sorry, I seem to have mistook post #2 for the OP. I think most of what I've written is still cogent. Let's leave it there.
I'm in broad agreement with most of what you've said. Can't comment about "Archbishop"s as I don't know that piece. I think the piece values are not far from the truth, except (always position will have final say):
1. I prefer two Rooks to a Queen.
2. I tack a little (indefinable) value onto the Bishop pair in my calculations.
Generally, I use: 1 3 3 5 9
It seems sufficient for my level of play.
Everybody knows that the values of chess pieces are 1-3-3-5-9
the dynamic value of the king should be about 4
My question is: how these values were discovered? Just empirically?
If I design a fairy chess piece , given its properties can I estimate its relative value?
For example what are the values of
a)the Fool of Omega Chess (The Fool assumes the identity of the last piece your opponent has moved.)
b)Capablanca's Archibishop (Bishop+Knight) and Chancellor(Rook+Knight)
c)The pieces in japanese and chinese chess (always on a 8x8 checkboard and no special rules as droppings)
Regards