RE: choke servo or optical kill
You can certainly be redundant on this topic, just as about any other setup preferences. Do you HAVE to? No. Do some believe you should be able to kill your engine with throttle trim, servo operated choke AND either a servo operated or fiber optic kill switch? Yeah... The redundancy can add additional points of failure, and perhaps in some cases, allow the modeler to avoid setting up any ONE way to kill the engine robustly.
Just take your time, setup your throttle correctly, with appropriate full range functionality, including shutting down the engine. And from there, adding any one other way to kill the engine should be sufficient, for piece of mind. Lately I have tended to go the route of a servo operated choke, due to several rear induction installations where manually choking is not nearly convenient.