SDL Question

[Rashid]

If I'm writing to an SDL Surface on the Freerunner via surface->pixels, where do I write? On the gpu or cpu RAM? 
Is there a difference when I use double buffering? Is it bad if I change the pixel pointer of the surface to an char array?
Must I free the pixel pointer before I do so? When I use a an array on the stack, will it be freed (chrash) when I keep using it several times?
Will it work when I made it static (heap)?

Greetz
rashid