Luther Strange and Roy Moore probably head into a run-off, and Strange wins with 55% or more because Moore might be too much even for Alabama Republicans.
At least that's my guess so far - Henry is too low name recog (probably ends up with 10-15% of the vote), and Moore probably beats out Brinson when it comes to the Christian Right (Moore at 30% or so, Brinson at 15% or so). Strange probably has a thick base of 40% - with other votes going to other candidates.
That's, of course, assuming the GOP field stays the way it is. It probably won't. I suspect a few more high rollers jump in - including, potentially, an establishment candidate that eats into Strange's vote total.
I think that is correct. Incumbents also generally have an advantage.