Is it permissible to metaphorically address an absent person by saying: "I miss you, so-and-so," or "I will hit you, so-and-so, when I see you," and is this considered Shirk?

It is not merely the saying that implies the representation and evocation of the one mentioned, as if he is seen and addressed, that constitutes shirk (polytheism). Rather, shirk is the devotion of acts of worship to other than Allah, such as supplication and the like. So, whoever supplicates a deceased or absent person, or seeks their aid, or seeks refuge in them, then this is the shirk that Allah Almighty does not forgive.