Aloha AllThisIsThatAndNotThat,
In the beginning and if you latter you have a physical illness, Chunyi will generally recommend spending 75% of your practice time during the week on active exercises and 25% on the guided healing meditations.
Both are for the same purpose, and the active exercise helps you focus and physically move to assist in opening channels and other systems of the body such as the lymphatic.
Chunyi teaches Levels One and Two in back-to-back "intensive" classes. You can be learning the level One active and sitting meditations AND learning/ding the healing steps of Level Two on others at the same time.
It is suggested to not add or replace the Level One active exercise with the Level Two until you've seen a shift in your physical situation - if you have an illness you're working on, or three months or so if you are doing well physically.
Much Love, and Happy Holidays,
Shawn