(Sorry if this is the wrong place, wasn't intuitive from forum page where questions should be asked).
Since i started playing the game i have had a difficult time settling cities. This is because i have to search far and wide to find settable tiles. This wouldn't too bad but the AI seems to be able to settle anywhere. It is something that has started to annoy me about this game. I wanted to play a medium map with 12 players, which would allow for a more crowded/rush feel. So i hurry pioneers at beginning of the game but cant find anywhere to settle. There are nice areas with green grass, forests, and rivers that are not in the immediate vicinity of my capitol- yet i still cant build there because the resource icons never show up.
These screenshots show the AI settling an area that i couldn't (note the red outpost since there was no where for me to place a city. Also note that i do have the option turned on).
Screenshot showing the map and no settleable areas.

Screenshot showing AI creating a city.

Screenshot showing options page.

So questions.
- How can the AI settle areas i cant?
- How to make finding an area for a second/third city easier?
- In longer games tiles will randomly become "settleable". No spells were used on them, these are usually tiles in between two of my cities. How/Why did they change?