pah. Gira, if i wasn't so bored of listening to your failboat plans i WOULD'VE ripped it apart....but by this point the holes in them are so numerous the plans sink by themselves, without assistance from me...
let's see...G4E...
hiring a group of assassins is much more difficult than it sounds. it's not like you can look up 'Elite Assassin Groups' in the yellow pages. even if you hire a group, there's no guarantee that they're not simply a band of common criminals promising to kill for money. government trained squads of spies and assassins have trouble getting into a position to assassinate one world leader, and that's after the country they work for has toyed with politics in such a way that it causes the target leader to expose himself for a shot. then you have the ridiculous amount of security that is placed around a world leader when they're exposed...
rebel groups are overrated. riot squads are made to deal with this sort of thing. simply sending a bunch of guys to cause mayhem somewhere isn't gonna get you anywhere. hell, look at Thailand. they had a huge riot due to civil unrest. literally hundreds of people involved, maybe more [can't remember the details. i remember it happened though], and yet, the riot squads managed to quell it after a while [though admittedly Thailand declared a national state of emergency].
climbing up the ranks of a government can take a lifetime unless you play your cards right. Look at McCain. he's 73 and still isn't president [sure he got close, but the fact remains he isn't].
disposing of an assassin group that is capable of taking out world leaders? chances are, by the time you find a way to dispose of them, they'll have already discovered and assassinated you instead. likely on the payroll of some other greedy power hungry politician that wants rid of you