Minor Faction Question(s)

Hello CMDR's.

I've moved to a relatively quiet system 2 days ago and decided to UP a minor faction's influence until i succeed in making them control the starport/system.Two days ago when i moved in they were at 4% INF, today i'm standing at 15.1% INF.

My questions are:

1. Can i induce war/conflict zones with the player faction that is present there? (Player Faction INF:14.2%)
2. If 1. is a yes, can i do that IF said player faction is going trough EXPANSION state? Or do i have to wait until EXPANSION state is over?3.If i have to wait, do i NEED to keep MY faction's INF less than 5% OVER Plyer Faction's INF?
3. If i DO induce a war state between my(npc faction) and said player faction and win, does their INF drop severely, or just the system security?
4. Is inducing WARS with all factions the best way to make them weaker (security and influence) or should i just focus on missions that increase my INF alone, will that do it or do won conflicts work faster?

EDIT: I want to eventually expel the player faction from this system (cause having them there bugs me), luckily it's not their home system. How long will it take from when their faction influence reaces 2.5% until they are actually Expelled from the system? one week? X number of ticks?

Thanks!