Well CKB is obviously going to be a single as they've done the video, single cover and radio edit in the last 2 weeks.
I think they will probably do a duel release, with CKB being sent to Pop, Hot Ac, Ac (and even maybe country (

Not counting on it though).
While Man Down will be sent to Rhytmic & Urban, but I actually think it will crossover to Pop, so that would effect both songs performance on Pop radio.
Man Down would actually smash in the UK, I've heard it on Capital FM (a big radio station in the UK) and they don't usually play album tracks but they played it. (It was late night though).