Four-Player Chess. How exactly to play?

Board and pieces
Four-player chess is played on an 8x8 board that is extended by three rows of eight squares on each side. Quite simply, this can be a 14x14 board with the 3x3 corners removed. The board has 14 files, assigned the letters a-n, and 14 ranks, numbered 1-14. The game is played with four regular sets of chess pieces, each of a different colour.  https://worldseniors2014.org  used throughout this book are red, blue, yellow and green.

Players
The game is used four players, each making use of their own set of pieces. The players will hereafter be referred to as Red, Blue, Yellow and Green, corresponding to the color of these respective sets of pieces. Red is the first player and always makes the first move. Therefore, the typical board orientation is from Red's perspective, i.e. Red is shown at the bottom. The next player is Blue, who's seated on the left side of Red. Yellow may be the third player and is seated across from Red. The last player is Green and is seated on the right side of Red, across from Blue. The overall game continues in clockwise order, i.e. Red, accompanied by Blue, accompanied by Yellow, followed by Green and then Red again etc.

Initial position
Looking from each player's perspective, the pieces are arranged exactly the same way as in regular chess, with the exception that for Blue and Green the king and queen are swapped. That is, the rooks go in the corners, the knights are put next to the rooks and the bishops are put next to the knights. All kings are put on light squares and all queens are put on dark squares. The pawns are put in front of the pieces. The board should be oriented such that the low right square of the 8x8 central part of the board is a light square, when viewed from Red's perspective, as being a regular 8x8 chess board. (If you might imagine a complete 14x14 board, the "n1" square on underneath right should be a light square.)

When it comes to files and ranks, Red's pieces are placed on the initial rank and the pawns on the second rank, Yellow's pieces are put on the 14th rank and the pawns on the 13th rank, Blue's pieces are placed on the a-file and the pawns on the b-file and Green's pieces are placed on the n-file and the pawns on the m-file.

Rules
You can find two main variants of four-player chess: Free-For-All (FFA) and Teams. In the FFA variant each player plays on his own and in the Teams variant the players across from each other form a team. Pieces move the same way as in regular chess and castling and en passant captures may also be the same.