Best fermentation cycle for this. Beersmith has OG around 1.75 or close
I'm guessing 1.075? I don't have any experience with the other questions as it pertains to vanilla, but you sure could throw in some wheat, oats, or lactose to build up a nice body and silky texture.
As to the fermentation profile, what yeast were you thinking about using and do you have fermentation temp control? That will determine a lot in that regard.