There's a Rum ration thread on the ship driver topic that may throw some light.
http://www.rumration.co.uk/cpgn2/For...pic/t=450.html
AFAIK, the USN definitely had a policy of allowing only aviators to command CV/CVN, but you have to have earn command experience on another ship before you get to be responsible for 100000 tonnes & 6000 bods.
WEBF - I wouldn't ask about plane guard let alone SAR unless you want to be very, very, very disappointed........As for Merlin, I very much doubt whether the wings could fold - in any case the storm lashing footprint for the beast is likely to cover sufficient space that you wouldn't notice the wings.