The default keybindings for moving is a bit counter intuitive, since moving towards the end of the movie is bind to UP, which indicates that frames are stacked with the first frame at the bottom, but this can be changed in the settings.
I prefer this configuration
Find the previous keyframe UP
Find the next keyframe DOWN
Removing unwanted parts
Find the first keyframe in the part to be removed, using play SPACE and fine-tune with UP (previous) and DOWN (next).
Set marker A ctrl+pageup
Find the last keyframe in the part to be removed, fine-tune with UP and DOWN.