Question 1: Ask him this question!
Question 2: You will not have a normal life. You will be a caregiver and a nurse more than a wife or partner. With no time off. It will get worse and worse. You will grieve all the way. You will have to summon up tons of energy to prop your partner up, and prop yourself up too. You can kiss your social life good bye, unless you belong to one of those tight-knit churches where members actually help each other. People will simply be unable to understand what it's like for you. Your life will be centered around the disease, especially as it progresses (and it will). Is this really what you want? Think hard, very hard about it. Unless you want to devote yourself totally selflessly to this man ... you are not getting into a relationship, you are undertaking a mission.
Question 3: As long as his needs are met, nothing.
I am sorry to have to tell it like it is, I wish you well.