I have the McNeill Chord System - It looks to be a very interesting resource, but for now it is far too above my head. I would prefer something to the basics. "Here are some scales, some songs, some chords. Get at it". Kind of like those MelBay Tenor banjo books, or the old CH/Classical banjo tutors from the 1800's - I learned very well with those on my 5 string.
Regarding your Charles McNeil book, if you want to play chord melody on your banjo, study the section that explains the entire neck with regards to how all the chords are formed and named by the specific string that is responsible for naming that chord form (pages 21 & 22.) For example, you'll see forms for major, minor and seventh forms that are all named from the root on the first string, another set for the root on the second string and another set for the root on the third string. These forms following one another up the neck. Start with going all the way up the neck with the C chord forms, then try the F forms all the way up the neck and then the G chords.
The Buddy Wachter video is great, but it covers mostly right-hand strumming technique. For left-hand chord work, the Mel Bay material mentioned earlier is also available for plectrum banjo, and covers all the 1st position (at the nut) major, minor and seventh chords. That's enough info for you to play thousands of tunes.
After you've mastered those chords, the book also includes basic 6th, 9th and 11th chords, as well as minor 7ths and augmented and diminished chords. There is also a chart at the back of the book which covers most of the common fingering patterns and their chords up the neck (chord inversions), so that you can begin to learn chord melody work. The Mel Bay books are often classified as "beginner materials," which they are, but they also contain more than enough info for very advanced music making. The Mel Bay plectrum banjo chord book should be available on Amazon for about $10.
If you also poke around on Amazon and search for "fake books," you can find tons of legit fake books with hundreds of songs, in whatever type of music you like. Each tune will have the melody line, the chord changes and the lyrics.
Good luck with the plectrum, and have fun playing it! SETH