Oddly enough, both of the points you bring up are handled perfectly by zsh's built-in correction. zsh will only suggest 'ls' for 'sl' if 'sl' isn't installed, a

Oddly enough, both of the points you bring up are handled perfectly by zsh's built-in correction. zsh will only suggest 'ls' for 'sl' if 'sl' isn't installed, and it'll catch 'fksc' and 'chomd'.