Normally I like to use the following optional rules.
- Victory Points for Leader Casualties
- Quality Melee Modifiers
- Isolation Rules
- Automated Defensive Fire
- Flank Morale Modifier
I don't ever remember using Cornwallis Cannon however, only certain scenarios suggest you use it (Found in the scenario description).
As for Rifle Fire Effects, there are some scenarios where it is suggested in the scenario description, when to use this rule. An example of this can be found in the 1st round of the 1776 Tournament we had.
www.theblitz.club/message_boards/showthread.php?tid=59477
Finally, Line Movement Disruption I have used before however, since the units in the EAW series rout so easily even without this optional rule in effect, I have been starting to stay away from it.