Some Whelen WAT bulbs no longer need a STC. They have now been FAA approved as a standard replacement. Now if you just have a landing light, and you try to change it to a taxi/landing light it will need a Stc. Because of extra switch and wiring.
If he is acting as pic, then the other person is a passenger during that time.
(1) Except as provided in paragraph (i)(2) of this section, no person may act as pilot in command of a tailwheel airplane unless that person has received and logged flight training from an authorized instructor in a...