Given the amount of times I've heard 'he's not on the same page as his team-mates' for Slimani so far, I think a full pre-season for him should be a requirement before deciding what to do with him, to be fair - if he starts fitting in better, then keep him as plan-B, or let him go and keep Ulloa if he's still interested.
Kap and Amartey I feel need games to get up to speed, which we don't have time for in the Premier League, so loan them out and see how they do.
Musa's quick, but that's not enough at this level. He'd do better with a lot more game-time, no doubt, but since he'd have to replace Vardy, it hasn't happened. Do we have time to keep him running in the background in case Vardy can't play? Is it worth it? Probably not, so let him go.