1. DIL is not a superset of JS, DIL is written in JS,
2. DIL code can be placed in the same file where you have AA appmeasurement code. DIL starts receiving data when you add this code in custom DIL : siteCatalyst.init
3. There is no need for AA to understand DIL, the main function of DIL is to collect data from front end site/app and also from AA or GA (google analytics) and send that to demdex servers (AAM).