I think the Browns are showcasing Osweiler to be honest with you. I know the Schefter report but that could be the Browns holding back knowing the Dolphins were not a good fit. Adam Gase coached both Brock and Cutler but Cutler is the better QB by any measurement. Also Tannehill is their guy so they don't need a young long term QB, they need a stop gap so Cutler is the best of both worlds.
I think the next starting QB that goes down, Osweiler's name will be batted around pretty heavily, especially if he plays well in week 1 and 2 of the preseason.
As far as Kizer, I'd put money on him starting games this year. We ALWAYS get to the 3rd QB in the depth chart at some point so you gotta figure he's going to play out of necessity if not from his performance.
It's good to pump the breaks on a rookie. Philly threw Wentz out there in week 1 and it worked out but generally, that isn't the best strategy. The Browns are going to put him out there when they feel he's ready or an injury happens. They aren't going to force him out there if they don't have to.