Advanced Options in game start

[Cheeseisgood]

Someone in another thread raised an interesting question - When you select "Random map", how many does it randomise from, and which ones?

I'd like to extend this, if anyone can offer a basic explanation on any of the advanced dropdown options. I generally set them all on "Random"

World Age - Not a clue.
Temperature - More/less desert?
Rainfall - The only thing I can think of here is Jungles?
Sea Level - I'd guess this one allows for larger/smaller landmasses?

Also for the "Resources" dropdown, the options are -
Sparse
Standard
Abundant
Strategic Balance

Those are all fairly obvious, but what does "Legendary Start" translate to? Will all civilizations recieve an area full of resources, or just the player? Or am I interpreting that wrongly?

 

[basta]

World age effects the degree of mountains on the map: older = flatter
Temperature--amount of tundra and deserts
Rainfall--amount of deserts/jungles, works in tandem with above
Sea level simply exposes more or less landmass than std maps.

Legendary start gives the player and all civs super-abundant resources near the capital