Glad to hear it 
What kind of control do you need? ArduSub is set up to allow control of the applied thrust across motion directions (in manual mode), and includes control algorithms for maintaining depth and attitude (orientation / rotation) in other flight modes.
If you for some reason want control of individual thrusters instead of making use of the frame configuration and internal control loops then that’s also technically possible, but requires workarounds as it’s not a functionality that’s directly supported by ArduSub.
I’ve moved your code into a code block so it’s readable - you can learn how to do that (and more) in the How to Use the Blue Robotics Forum post.
The code you’ve posted is from our Set Target Depth/Attitude Pymavlink example, which shows how to set the desired depth target or attitude target when using the depth hold or stabilise flight modes.
Which parameters are you unsure about? The explanations of the parameters used by each function are specified in the function doc strings, and the comments in the code describe each step that is taking place.