Hi Tim,
Your questions were:
Can we use SL Appendix rules?
What COI Supplemental Rules are in play for the COI game?
Your questions regarding the SL appendix and the COI Supplemental rules are covered in the Squad Leader Academny Conventions.
Answers:
SL Appendix rules can be played by agreement of both players. Keep in mind that these will add complexation and delay to the game. I personally will not be using these.
The COI Supplimental Rules in play are B: ARMOR CREW MORALE, J: RUSSIAN ENTRENCHMENTS and M: LOCATION OF HITS.
Others only can be used by player agreement prior to play.
Monty