If you have little Linux experience it makes no sense to use a niche distribution. You have a lot less people to ask for help, you will find less documentation and support and you will be frustrated really fast, because your niche distribution is doing something different than everyone else, which will break something and you cannot repair it. If you are a beginner go with one of the big ones.
That depends on what happened. If the whole structure collapsed instantly, they are probably crushed by debris and a shockwave. But if there was a “leak” and the pressure equalized without complete destruction maybe the lungs are compressed, ribs broken and eardrums torn. All depending on the speed of equalization. Maybe also bones break (because water is compressible) but the bag of meat and blood should remain intact. So finding a body would help to reconstruct what happened. But I doubt they will find one before hungry animals do.
If it results in death when the controller stops working, you have a serious issue with the system architecture and should work on that instead of trying to improve the controller.
I also use it. Big benefit is also that you don‘t need a special software to access your backup.