I might have missed it being 1 giant paragraph but why are you dealing directly with the other guy's insurance. Put it thru your insurance and give them the video and other evidence. They will hash out who pays what.
It normal for you to be required to secure the item from further damage or they may deny coverage for later damage. Lots of pictures and videos then secure any holes from the weather. Also, as soon as the storage place turned, get approval from your insurance to get it out of the storage place.
Suing for profit is a low odds game and as you were told, the lawyer will likely claim most of it.
At this point it's probably best to put it in the rear view mirror as soon as you can.