I'm assuming that speed is relative to earth...

A few nitpicks...
would come within 20,000 miles of Earth — close enough to hit some weather satellites.
And miss all the others?

would crash into the planet, or could land in the Pacific Ocean
Land?

If an asteroid hits Earth, Oppenheimer says there are only two things that people can do: Move out of its way or move the asteroid itself.
I would say that when it hits the Earth, it's already too late.

"The best thing to do, actually, is to fly a spaceship up to the asteroid and attach itself,
Not really a nitpick, but I would think for this particular "rock" that the rocket option to shift it's next pass would be extremely difficult due to having to rendezvous so far away. (quite a chace)