1/ recoveryDividers can be used on any items marked with specialType (with specialType > 1 and specialType < 200)
Elerium is not a special item normally, but maybe in the XCOM Multimod it is.
More info:
https://openxcom.org/forum/index.php/topic,6616.0.html2/ There are many places that can be considered as beginning of a mission...
The script hooks currently available are:
a/ createUnit - runs when a new unit is created
b/ applySoldierBonuses - runs just after createUnit
c/ newTurnUnit - runs every turn... you can check if it's turn zero (or turn one, not sure) to perform the functionality only once
d/ createItem - runs when a new item is created
e/ newTurnItem - runs every turn... again, you can check if it's the first turn