Usually, you get pretty good results with 256x256 pixels - often lower if the texture is cleverly made. I would not even consider photo quality textures (which thread was that?) Maybe that could get nice(er) rendering, but the time involved is beyond my patience and processor...
In short - try good small textures, edit with a good picture editor (like the Gimp) if need be. And you can ask in the forum. I have made a few seamless textures for my own work, and I am happy to share if I know what you are after and I have one.
Lighting is an art - in photography as well as in SH3D and the real world. Don't think that can be summed up in a post. As is colour balance, by the way. Camera shutter speed is not really relevant (as long as camera is steady), aperture, however, will let you play with depth of field (that is, increased sharpness over distance).
And - trying and failing is usually a good way of finding out what you want
And if you share your results, you might just get a tip or two... ok