and the texture image file.

I've posted this question in another forum but with no response could you help out? ( forgive the noobieness of them )

1 - Is 72dpi the only resolution maya will import image files in at?

3 - To get the highest quality render should I create my image plane to be the size of A3 use a 72dpi A3 tiff image, then in render globals set everthing to highest quality an the pixel to A3 measurments? basicaly what I don't understand is if i'm only using a 72dpi image file how can it produce a 300dpi A3 quality render from it?