software

it is my understanding that you file a slight intend into your saddles for your string to sit in. I don' want to go as deep as the nut, so just a good groove for the string to rest in. Am I correct? Also, I am looking to buy a set of files, and which maker/line do you suggest to do both nut and saddles?

To do the saddles, you could get away with using a set of jeweler's files, namely a triangular-shaped one. These can be found in most hardware stores. To do the nut slots, you'll need files designed for this purpose. You can find a cheap set thru Stewart-MacDonald guitar supply.

what do you do with the triangular file? do you really want a triangular notch in the saddle? How deep do you go?

The triangle shape file will give you the most narrow filing surface. You needn't go too deep on the slot; just enough to prevent the string from moving side to side. Come to think of it, you may be able to file the saddle slot with the nut files. But it wouldn't hurt to have both types of file sets in your toolbox for guitar repair.