A lot of those Finder options are just going to increase noise on the screen. It's rare that I ever need to know the full path of something in OS X. Either I'm already on the command line, or I just use Spotlight.
Disabling the “Are you sure you want to open this application?” dialog seems just wrong. Confirming once per program downloaded from the net seems like a sane default.
Anyway these are pretty subjective things. Good thing they're so easy to pick and choose from and revert.
Can you provide an example of an external display on which it's not necessary or harmful?
I will never understand this.
The quarantine is the bit that causes a dialog to pop up the first time you attempt to open a file newly downloaded from the internet that has the executable bit set. Good for catching, say, executables disguised as documents, or stopping anything from exploiting a browser hole to get an executable downloaded to your machine and opened by your browser.
Other than that, looks great :)