It looks like the scenery color is darker closer to the aircraft as you fly along, and in the distance, it fades to a lighter color
That's just normal, the ground is made with two layers, and the overall color is a mixture of the base layer and the detail layer. Since the detail layer is not loaded when not needed for obvious performance reasons (you won't be able to see the details after a certain distance), it's normal the overall color would change.
It loads in square tiles as you pass over the scenery.
That's normal as well, since the scenery is made in tiles, like any other scenery out there that uses an higher resolution than FS9 would otherwise allow with photoreal scenery.