What licensing requirements are necessary when carrying a passenger?
In order to carry a “passenger” you have to become a licensed general aviation pilot, build your powered parachute as an amature built aircraft, get an N number for it, and treat it like a GA airplane. An alternative to that is to become a powered parachute instructor under one of the exemptions to FAA Part 103. As an instructor, you can not take up a “passenger” but you can take up “students”. The paperwork is a little more of a hassle, but it is still an easier program to work under. All of this will change within a few years as a new FAA rating called Sport Pilot takes effect.