I dunno, if all the templars are truly addicts, then if the withdrawal symptoms are strong or unbearable enough, then maybe that's why we have Red Templars? At least, some of them anyway, not all of them. But I didn't think about Josephine and her connections, oh good. *relief* This means my Quizzy won't have to tie Cullen to a bedpost or something while she goes off to find a solution/more lyrium/a cure.
I did say my thought about his crisis point was farfetched. although I don't really think my Quizzy would need an excuse to tie Cullen to a bedpost *whistles*
I think it is a given that the Chantry used lyrium to control the Order. We know that Alistair definitely says as much, and I know Evangeline says something like, "Once you're in the Order you can never leave," when Rhys comments on her being addicted to lyrium in Asunder.
I think the advisors might be able to die? Although I'm just going off of the E3 demo and the cruel cruel clifhanger they ended it on with Leliana and the knife to her throat and the look in her eyes. But if they can die, then I think as players, we'd have to try really hard to get to that point? Since the advisors are super important and all. It would definitely make the game a lot harder if we could lose our advisors in some way. Say you lose Cullen, so your troop numbers start diminishing because he isn't there to lead the armies in your stead, or if you lose Josephine, you start losing resources and alliances because you can't meet the requirements for trade and political deals she had made, and if you lose Leliana, it becomes extremely hard to keep an eye out on what's happening in the different regions, even the ones you have control of, because you've gimped your intelligence branch.
But again, I'm only going off of the E3 demo. I don't think that they advisors can die, because again, they're super important and they seem necessary to the gameplay as far as running the Inquisition goes.
Umm I'm kinda hoping we may need to do this, but for a different reason... 
I was thinking maybe those templars sought out the red lyrium to increase their current abilities, I wouldn't be surprised if they did so because of the mage-templar war and wanting an advantage over the mages. We'll probably encounter mages abusing red lyrium as well (red lyrium was in the demo at Redcliffe castle, no?).
I'm starting to believe that maybe advisors can die but are harder to die than companions because of the significance to the game play. I think you're right as well, losing an advisor will really take a toll of the inquisition and the impact on game play. You will probably find that certain missions will not only be offered but maybe even non-achieveable, as in you might be able to get the missions but never able to complete it.
I'm thinking I might start a list of theories and when the game comes out I can see how far off or close I was to getting things right.