Notes:
Also note that invade_priority plays an important role in which forces invade where and when.
Cavalrycmdr has said he thinks that the invade_priority is offset by distance from a target, which can make or break naval invasions. And personally I agree as it seems like a pretty good explanation for some of the things that happen in the LTGD logs.
Invade_immediate also may affect naval invasions, although invade_buildup works too.
1) can_force_invade , turns on or off invasions ordered by the exe and overriding the decisions unless otherwise specified
2) See here for further reading