Have a look at the thread at
http://www.luminous-landscape.com/forum/index.php?topic=62609.0The link that explains a lot about resolution is
http://www.digitalphotopro.com/technique/workflow/the-right-resolution.htmlColour space choice is less empirical.
Using a wide gamut space like ProPhoto may gain you extra achievable gamut, but you need to be aware that you may not see that extra gamut on your monitor, so take some time to learn soft proofing to avoid unpleasant surprises.