One, although it's probably screwed in too tight anyway.
One. Apparently she will screw anything.
The edge of a cliff, you are guaranteed she will push back!
When the Doctor changes the timeline, it's usually for a good reason.
Both of them
Two, but how do they get in there
More guns.
An Optimist learns German. A Pessimist learns Chinese. A Realist learns AK-47.
The optimist sees the light at the end of the tunnel. The pessimist sees nothing. And the realist sees the train.