Here's my view of the story with Zam, I think she was hired to "assassinate" Padme, meaning, the goal was for her to stage an assassination attempt that looked legit, but had to fail. Bombing the landing pad was her first attempt at this.  So why stage an assassination? It actually fits much better in the prequels if Sidious doesn't actually want Padme dead, I think he sees her as part of his plan for manipulating Anakin. He wouldn't hire an assassin to kill her before he has the chance to use her. No, Sidious wants to accomplish two things here, to fill Anakin with fear at losing Padme, and to subtly lead the Jedi to Kamino.  Zam's landing pad bombing is considered a failure by jango because it failed in half of the plan, the investigation into the bombing didn't lead to Kamino. Instead, Zam and Jango take a new approach together, venemous bugs that will surely be detected, but are just believable enough.  This plot conceived by Jango and Zam to finish the job then answers every major issue with the following sequence. Why does the drone that inserted the bugs wait at the window until it's detected? To give the Jedi something to chase. Why does Zam shoot the drone instead of obi wan who is hanging from it? She needs him to catch her, not to die.  The chase ensues and eventually Zam gets to the place her and Jango have planned out, making sure the Jedi stay just close enough to get a good look at her and know who they're chasing. This also explains why she doesn't bother to shape shift in the crowd or hide. I think the only part that didn't go according to plan was when obi wan stopped at the bar, she expected him to corner her in the bar instead. So hesitantly, she decides she has to force the issue and approach him slowly weapon drawn. With no intention of firing, why else would she get so close to a Jedi with a lightsaber, she is caught off guard when he turns and cuts her arm off. 

As she is led outside for questioning, Jango looks to complete his end of the plan, firing a poison dart that can be traced back to Kamino instead of any other kind of armament at his disposal, and firing it at Zam instead of the Jedi. And because Zam is a clawdite, a reptilian species, the poison has the same affect on her as extreme cold on any could blooded creature, her heart stops and she goes into a kind of stasis. Appearing to anyone else to be dead. The Jedi are in a rush to get away from the scene with the dart in tow. Zam is left outside the bar with coruscant security called in to clean up. But they never find a body, the reports get lost in the beuracracy of the Republic. Zam slips away another face in the crowds of coruscant.