As I noted early on, now we have defined the "problem" you want to solve.
First, you need to understand several things. Those are (1) color temperature of light sources, (2)color balances of film stocks, and (3)filters to convert light sources from one temperature reference to another. It isn't magic, but it isn't trivial. And there are a lot of great older books floating around on the subject. I would also bet that there are a lot of good internet resources, too. Maybe someone can point them out.
As far as scanning is concerned, Lee is right, DPUG is a better resource. And there are some other good groups dedicated specifically to scanning as well.
But you are correct that your first problem to solve is getting the exposure correct on the film. And that problem is solved by understanding your (1) light source, (2) film balance, and (3) filter selection if the light and film don't match.
For that part I suggest that you first search the archives for stuff on the subjects (which I personally always find frustrating as hell), then after you've confused the daylights out of yourself (or maybe the tungsten lights) go to the Color: Film, Paper, and Chemistry forums and start asking a few questions about how Tungsten vs Daylight film react to various light sources.
As for the gray card, I suspect that you'll eventually end up using both a gray card and something like a McBeth color checker if you are doing very critical work.