Firebug
Not-so Great Engineer
Seems very interesting (although I'd add a little more things involving Forests personally). However, is that ships sailing through rivers actually codable?
Well. I guess i could ask one of the long time modders. I'm sure they would of tried it at some point, if it was though....
I know it's normally not well seen to point out someone else is working on the same civ, but... your concept is pretty damn similar to Tomatekh's Kievan Rus.
I tried to avoid that, and i don't think it is too similar. I guess the UU is similar.
production towards
religious buildings in all cities with a source of fresh water. Units gain 1% combat boost near sources of fresh water per each 3
), but it is also cheaper and may move after attacking. Has 5
movement. Upgrades to the Ironclad.
gold from
trade routes per each domestic trade route they receive. Specialist buildings generate +1
GP point of the appropriate type per each trade route sent to and from the city. National wonders increase the number of 
food, +2
culture and a
great work of writing slot that when filled gives +25% 