re: LLC question

He could sign a will that leaves it to you, but he could change that the next day.

Folks in this situation often get a business lawyer to prepare the LLC operating agreement up front to contain provisions such as a buy-sell agreement, which triggers on events such as death, divorce, bankruptcy, etc. You also want transfer restrictions/right of first refusal so he can't sell his share to some idiot if he gets hard up for money or tired of the company. And you want some form of tie-breaker if you own the LLC 50/50 (popular, but often a bad idea).

Review your operating agreement and see if it already has such provisions. If a decent lawyer drafted it, you may already be covered in some fashion.