How to Train with Injured Shoulder(s)

any tips to how to come back from a shoulder injury, thing you can do while you are going through rehab
volumen of trining ?
load ?
meds to help with pain
exercise selection
stuffs you can do to minimize the lost in upperbody muscle and strenght

All depends on the specific injury to the shoulder. You have provided way too little information for anybody to give substantially helpful advice.

And every shoulder is different. I remember my surgeon saying that repairing a torn meniscus was textbook but that shoulders are so individual, including the rehab process.