Settling on a resource:
1) When you discover the technology which grants the ability to build the improvement which accesses the resource you automatically get access to the resource. E.g. building on iron will grant you access to the iron if you have mining, building on spices will grant you access to the spices if you have calender.
2) A city always produces 2

, 1

, and 1

. If the tile on which the city is built produces more of any of these three outputs then the city tile will also produce that excess output. E.g. a plains hill gives 2

so a city built on a plains hill produces 2

. This does not apply to features, which get destroyed by the act of building a city (floodplains and forests), but it does apply to resources. Consider copper on a flat grassland tile and a flat plains tile. The first tile produces 2

and 1

. The second produces 1

and 2

. Building cities on these tiles will give 2

, 1

, and 1

, and 2

, 2

, and 1

respectively.
3) You will not gain the tile improvement bonus if you build a city on a resource. E.g. a city built on copper on flat plains will get 1 production more than usual but you won't get any of the bonus production that comes with building a mine.
Personally, I never take account of resource location - just eventual city output. If building on a resource means that I get more of the type of output I want (is it a production, commerce, sceince, or great person city) then that's the smart choice. Wines feature near the top of the list of resources that I regularly find myself building cities upon.
It seems you can't have more than 15 smilies in a post.