Give whatever civ you're playing as luck bonuses an/or choose the Universalists as you political party.
That should end your dilemma.
AFAIK luck has no effect on minor or mega events, or what anomolies you find, or what tiles appear on a planet, or if you get a colonization/ethics event--i'm pretty sure the only thing it does is boost your weapons minimum roll value (so if you have a 50% luck bonus, your weapons will never* roll less than 5, and at 25% you'll never* roll below 2).
*note: you may still observe values of 0 if the ship you attack has good defenses.
Ermmmm, some events can be prevented by having good espionage on other AIs.
what event or events do you have in mind? i'm not challenging you, i've just never observed a connection between espionage and events.
That would depend on if the events are truly (code-based, of course) random, or if they are generated by certain influences.
my sense is that it's a little of both. it'd be nice if the devs made some of this stuff a little more transperant, but i'm not about to stop playing over it.
Is there any way to kill off these wannabe assassins? Or at least stop them from killing people, and starting a war that eventually destroys my civilization.
when it happens, load your last auto-save... i think that's about all you can do.