If I changed a NPC AI packages in CS would the changes take effect in a saved game?

I know they would take effect in a new game, but in a saved game I have had mixed results. Therefore the question as in the title, what information is held in saved games?

I know you can change certain things like non-leveled clothing and armor, inventory, NPC's stats, race and appearance and the changes are applied to saved games and these changes appear to stick forever.

But you can't change a NPC's gender, thats is set in the saved game and can't be changed, Also, leveled items in inventory will reappear after a few ingame days even if you delete them in CS and remove the items from the NPC ingame, so that must be stored in the saved game.

Is there a page somewhere that lists what information a saved game holds, and what information can be changed via modding to effect a saved game and what information won't be affected by modding?

Also in case of a NPC that respawns, what respawns...the information held in the saved game, or the information in the oblivion esm with mods?

Cheers