About Eli and the kid that gets operated on.
! Well Kojima confirmed that, it was Paz in the trailer.
Source: http://gamingbolt.com/metal-gear-solid-v-paz-confirmed-as-patient-from-trailer-bipedal-mech-playable
! Also about Eli being Liquid, theres a few hint besides similar facial features. For example, Eli sounds like the the biblical figure "Eliab" who was the eldest of 8 sons, and the youngest of the brothers was named David which was the guy who became the king of Jerusalem after defeating goliath. There were originally 8 clones and Snakes real name is David so yeah..
Besides that, Liquid are able to speak Arabic like a native due to his time in the middle East, which seems like the place where the game is set but who knows at this point… Some also points out that the teeths on his necklace looks like jackals teeths, which refers to the line in MGS1 where Liquid kills Grey Fox where Liquid says that, in the middle east they don't hunt foxes but jackals.
The name could also be short for Elijah, which is a character in Moby Dick like Ishmael. But i haven't read Moby Dick so i don't know about that character..
Also really looking forward to this game, especially because of Ocelot and Kaz. Maybe instead of Raiden camo as a child soldier then it would be Drebin. I could see it happening..