I'm in the same boat with Jason on Cassel. I'm not 100% sold but it's night and day compared to early in the season. His biggest weakness IMO was his tendency to hold on to the ball too long, and that's not an issue any more, and his accuracy on his deep passes has gotten a million times better this season. And his contract will ensure that he's the starter here for the foreseeable future.
I'd vote pass rusher first, WR second, backup QB third on the draft priority.