Two questions:
1. May a piece which promoted move out of a citadel, move back in on a
later turn, and promote again? There are three possibilities for this:
Firzan--Eagle--Queen
Vizier--Lion--Warlord
Guard--Champion--Supercav
2. Let's see if I understand promotion zones:
A. Either citadel on the enemy side may be used by any piece which has a
level to which to promote.
B. A bishop may also promote on the square orthogonally adjacent to an
enemy citadel. (In other words, a colourbound bishop still has two
promotion spaces.)
C. A pawn may also promote on b2(b7) or k2(k7).
3. The ZRF is barely started, but if you want to send me your email addy
(mine is on the feedback page) I can send you a screenshot or two of the
graphics I did for this. I went with an unchequered board to supplement
your historical feel.