In Bond's universe, microchips are actually created in Silicon Valley.
As Roger Ebert said, Zorin's plan is idiotic, because the companies in Silicon Valley don't create microchips, they create electronic products that use microchips, so he's actually trying to kill his own customers. But Zorin didn't think that in Bond's universe something might be difficult. This is a world where all villains are too dumb to shoot at Bond and try to kill him by Death Trap instead. Why, in this world, couldn't they have made Silicon Valley the world's greatest storage place of microchips instead?
Zorin thought Mainstrike was still going to happen when he was up in the blimp
Otherwise, why would he have been so chipper?May Day is guided more by blood lust than being strategic
Killing Lee and Tibbets were more about satisfying carnal desire. They were both strategic bad moves. Killing Tibbets would have tipped Bond off and allowed him to escape, but she saw an opportunity to kill him in a clever way. Killing Lee off would have also tipped Bond off if he tried to contact him. She's probably caused a lot of unnecessary deaths just for fun.