I've all read speculations about who might get what and behave in what way in many threads and then decided to create this thread to give these speculations a place without disturbing other threads.
Russia
We know nothing about Russia besides that is lead by Peter I and we've seen some border colors that resemble civ 5's Russia. Multiple times I've read speculations that Russia might be a science focussed civ because of Peter. But Russia leaves lots of room for other things imho.
Arabia
We've seen that the UB, the Madrasa, is a temple replacement. Presumably it helps with science in some way. Speculations seem to be that it will be a religion focused civ, also military because the rather militaristic leader. Saladin may have an agenda that has to do with conversion of cities of his religion, or spreading religion in city states.
India (revealed, agenda still unknown)
The UU is the Varu, a war elephant that comes quite early in the game. We've also seen a unique improvement called step well. Maybe step wells generate fresh water on tiles that would have no access otherwise, generate extra housing, boost adjacent farms? Seems to me, that besides reading the wish of it being a religious focussed civ, it's once again about high population. Gandhi's agenda? Maybe he hates warmongers or people that spread over many continents.
Sumer
Nothing known besides the leader. Since the most famous buildings of the sumerian civilization seem to bee ziggurats (potential shrine replacements) and canals (potential unique improvement) one of them might get in. Personally, I picture Sumer as a science/tall city civ. Surely their UU has to be something early (Slinger replacement?). I can imagine Gilgamesh not liking people that are technologically ahead of him, but that would be a horrible agenda. Gilgamesh might have special walls or irrigations system.
Greece
Unique District: Acropolis replacing the Theatre District. This might create extra culture, might give adjacency bonus to nearby campuses or holy sites... many possibilities. Since we have two leaders, the focus of the civ is probably cultural and then Gorgo is more on the military side, while Pericles is more about science. UU's are probably early, like the hoplite or the trireme. To me, a bonus on governments or policies seems also plausible. Pericles might like people who share the same government even more than others, or he likes big fleets.
Rome
UU: Legion that replaces the Swordsman. UD: Baths that replace the aqueduct. Many ways this can go. Will Legions once again be able to build roads? Or forts? Or a movement bonus for them? Will baths generate culture besides giving what an aqueduct gives? What may it be focus on? Culture and Military? Expansion? Tourism? Trajan might like big empires and hate tall ones.
Kongo (revealed)
UU: Ngao Mbeba replacing the Swordsman. Maybe not requiring iron? I have no idea how this civ will work, speculations seem to be on religious. I can also imagine a science or culture boost from friendships as a ULA of Afonso, this would make especially sense if his agenda is that he likes people with a lot of culture. UB/UD/UI not known yet.
Norway
The UU is the Longship that is a galley replacement. Since this is very early it may have a special ability, maybe it can cross oceans? Th UB is the Stave Church, a temple replacement, I have no idea what its difference from the normal temple might be. The ULA might be military, while the civs UA may be commercial or amenity related. A bonus from tundra tiles did come up, too. I can also imagine one from coastal cities.
Spain (revealed, agenda still unknown)
Spain is already revealed and we know the bonuses. What we don't know yet is Philip's agenda. May be something with religion (but surely not the same as Saladin's).
Russia
We know nothing about Russia besides that is lead by Peter I and we've seen some border colors that resemble civ 5's Russia. Multiple times I've read speculations that Russia might be a science focussed civ because of Peter. But Russia leaves lots of room for other things imho.
Arabia
We've seen that the UB, the Madrasa, is a temple replacement. Presumably it helps with science in some way. Speculations seem to be that it will be a religion focused civ, also military because the rather militaristic leader. Saladin may have an agenda that has to do with conversion of cities of his religion, or spreading religion in city states.
India (revealed, agenda still unknown)
The UU is the Varu, a war elephant that comes quite early in the game. We've also seen a unique improvement called step well. Maybe step wells generate fresh water on tiles that would have no access otherwise, generate extra housing, boost adjacent farms? Seems to me, that besides reading the wish of it being a religious focussed civ, it's once again about high population. Gandhi's agenda? Maybe he hates warmongers or people that spread over many continents.
Sumer
Nothing known besides the leader. Since the most famous buildings of the sumerian civilization seem to bee ziggurats (potential shrine replacements) and canals (potential unique improvement) one of them might get in. Personally, I picture Sumer as a science/tall city civ. Surely their UU has to be something early (Slinger replacement?). I can imagine Gilgamesh not liking people that are technologically ahead of him, but that would be a horrible agenda. Gilgamesh might have special walls or irrigations system.
Greece
Unique District: Acropolis replacing the Theatre District. This might create extra culture, might give adjacency bonus to nearby campuses or holy sites... many possibilities. Since we have two leaders, the focus of the civ is probably cultural and then Gorgo is more on the military side, while Pericles is more about science. UU's are probably early, like the hoplite or the trireme. To me, a bonus on governments or policies seems also plausible. Pericles might like people who share the same government even more than others, or he likes big fleets.
Rome
UU: Legion that replaces the Swordsman. UD: Baths that replace the aqueduct. Many ways this can go. Will Legions once again be able to build roads? Or forts? Or a movement bonus for them? Will baths generate culture besides giving what an aqueduct gives? What may it be focus on? Culture and Military? Expansion? Tourism? Trajan might like big empires and hate tall ones.
Kongo (revealed)
UU: Ngao Mbeba replacing the Swordsman. Maybe not requiring iron? I have no idea how this civ will work, speculations seem to be on religious. I can also imagine a science or culture boost from friendships as a ULA of Afonso, this would make especially sense if his agenda is that he likes people with a lot of culture. UB/UD/UI not known yet.
Norway
The UU is the Longship that is a galley replacement. Since this is very early it may have a special ability, maybe it can cross oceans? Th UB is the Stave Church, a temple replacement, I have no idea what its difference from the normal temple might be. The ULA might be military, while the civs UA may be commercial or amenity related. A bonus from tundra tiles did come up, too. I can also imagine one from coastal cities.
Spain (revealed, agenda still unknown)
Spain is already revealed and we know the bonuses. What we don't know yet is Philip's agenda. May be something with religion (but surely not the same as Saladin's).