Great report, thanks for sharing it at an obviously difficult time. Glad all is well and everyone safe. I hope your brother heals quickly.
A few observations; this shows how difficult an rescue is. Even with training and practice, the real thing is going to be different. Emotions run high, confusion abounds, glad you kept it together, you did an excellent job. Another point is the importance of one person taking charge of the rescue. With so many people trying to help it is even more important that one person, Andy would seem to be the best here, should be trying to control the situation. Organizing who will be probing, shoveling, searching etcetera. If for no other reason then to get everybody in search mode. I know it such situations everybody wants to help, but it is critical to organize such help, or pandemonium ensues. Finally, the non-functional ABS should be a non issue. If you would ski a run because you have it, verses passing because you don't is a good reason to pass on the line any ways. Sure it is good to have the safety gear, but it should not be giving extra confidence to ski sketchy lines. I am not making any criticisms, but relaying some thoughts that came to me while reading this. In the end I am very glad everyone came home with only some significant, but heal-able injuries.
Peace