1. Cash buying a unit while is being built gives a completely new unit and production that turn continues on the one partly complete. 2. Cash buying a building partly complete wastes the hammers that already went into it. No, the discount was removed from the code base while Vanilla was being developed. As a side effect, you can see where they commented out the AI code to cash rush things that was optimized for Civ IV's rushing partly completed items. Culture to get a new tile: Goes up every time the city grows via culture. Tradition opener and a specific world wonder both give discounts on this. Note that the culture cost stays the same when you spend cash to buy a tile. Cash to buy a tile. Each time you cash buy a tile, cost to cash buy go up. Tough terraign costs double that of light terraign. Tiles with a known resource though get reset back to lowest price. Playing America and building a specific world wonder both give discounts on this. No, the only thing that causes GA turns for the next one to be reduced is using a Great Artist to triger a GA. However, the counter to a GA does not change while in one, so if you were close to a natural Golden Age, triggering one via policy would slow down the natural one. That one is probably the defense value of the city which doubles as the base factor when the city bombards a nearby unit. Every single version of Civ features an AI with a handicap on Prince. In Civ IV's case the most obvious one with the AI's major cash discount on upgrading units (it usually could upgrade its entire army the turn it got a new military tech). That was toned down in the BTS expansion but still there. It also had a major (but hidden from the player) inflation discount. In Civ V case, the most obvious one is its happiness bonus. Prior to BNW, it had the Chieftain one. Now it's the fixed flat bonus from Chieftain plus a percentage close to Warlord. However, with BNW, the AI got a brand new bonus with a Science discount bigger than a Human on Settler would have. (But you won't notice the AI's science discount since it doesn't prioritize science buildings enough) Also note that the Civ V AI needs its bonuses a whole lot more than Civ IV did. Civ V reintroduced things from Civ III that were disallowed in Civ IV because the AI sucked so completely at it and in addition introduced new mechanics that are much more difficult to train an AI to do well.