Though I'm hardly a fan of this storyline, I do want to point out a few things I think were not touched on.
A) Stark did not want to murder foreign dignitaries. He ensured Osborne only had a weak gun that he knew couldn't kill an Atlantean.
There is, in fact, a plausible explaination for a lot of his Machiavellian actions.
Namely,
he had no choice.
When Stamford happened, that was that. The jig was up. He knew it, Reed knew it, Hank Pym knew it. There was no hope of further review of the SHRA, of a refinement of it's terms. Anyone who tried to block it would be trampled under in the wave of blind public rage after Stamford. So as a result, a law that was still under review and refinement was on the fast track to passing.
What do you do?
Tony knew that there was no real hope of forcing the government to back down. The entire country was behind the act, what're they going to do? Refuse to protect America from alien threats, Doctor Doom, etc? Are they going to fight their own country and compel it, by military force, to back own from the law? Those options don't work at all. Nor can you wait for the government to refine the law after passing, since who knows how much damage would be done in the interim?
The only option, then, is to play along, intending the entire time to protect the interests of his friends.
To draw a fun allegory, think of the Psi Corps from Babylon-5. Founded to protect normal humans from telepaths by keeping them registered and in control, but easily co-opted by the telepaths themselves....
Although I disagree with the "provoke the Atlanteans to cause a crisis and unite the heroes" element (Frontline's writers have not impressed me very much), it's pretty clear from this point that Tony never intended to leave heroes in the Negative Zone. He was working for an amnesty since day one, and it ironically might've been Cap who delayed it by maintaining the resistance.
I don't necessarily agree with how things went, or even the plot itself, but I feel this is an alternative to the "OMG Tony is now EV1L11!!!!1!!" standpoint.
As for Bishop, besides getting screwed by Millar with that dumbass "I thought we were the Avengers" line in Civil War #7, I found that Civil War X-Men #1 explained his motives better. Namely, he's holding out hope that the SHRA might prevent this timeline from becoming the same as the one he grew up in. Certainly an understandable motivation, especially if the SHRA didn't happen in his timeline
And that's my two cents of wisdom for you.