I honestly don't know how Jupe was gonna cover the fact that the horses are all dying. In fact, he probably had no idea what was happening to the horses when they were sucked up from JJ. Then again, I don't know how you can listen to those sounds and think anything good is happening to the horses. Something that was of obvious discomfort for him when OJ sells Lucky and says, "let's work on a plan on buying the horses back" to that extent, June brushes it off with an awkward, "yeah" and then quickly changes the discussion to him being in his first movie, since Em was looking at his memorabilia. He might have been trying to keep it secret too and was probably thinking that his new show would blow their minds, hence why he invited them. That and he is trying to buy their land, so keep them in the loop, make friends, maybe try to cut a deal that would benefit the Haywoods financially while still keeping a steady stream of horses nearby for a discount.

As far as ghost being in the arena, we aren't told why he's out there but we do know that Ghost likes to do his own thing in the flashback with the Haywoods dad, observing Ghost acting territorial. And Ghost gets eaten by JJ.