ENY - When one country gets an overwhelming advantage in numbers over the other two countries. ENY will stop them from flying "good" planes such as La-7's and Spit16's. ENY really does not affect perks except for keeping you from flying them.
Example: Bish - 134 Nits - 98 Rooks - 95, Bish would have an Min-ENY that will prevent them from flying "good" planes.
NOTE: # In-Flight does not affect ENY, it's how many are on that country currently whether in-flight, in-tower, or afk.
OBJ - OBJ just tells you what plane/vehicle will get you the must perks for destroying objects (buildings, ammo factories, etc etc).
Example: A plane with OBJ of 5 won't get you as many perks for destroying a town building as a plane with an OBJ of 20.