Off the top of my head...
For a Bohemian pilsner, you don't need any salt. Use distilled, and adjust pH by adding about 4% acidulated malt (well, exchange it for part of the pilsner malt).
For just about any other lager, use about 1 to 1.5 teaspoons each of gypsum and calcium chloride.
For styles known for having very hard water (e.g., Dortmunder), you can probably go a little higher to 2 teaspoons each.
For any beer containing a reasonable degree of dark roasted malt (e.g., schwarzbier), you can optionally add about 0.5 teaspoon of baking soda. But personally, I might not do it, and if I did I would add it to the boil, not the mash.
If you want to use any epsom salt, sprinkle it in like a tiny amount of fairy dust -- you do not need very much of it at all. We're talking like 1/10 of a teaspoon or something like that, and this goes for any and all styles. But I find it is optional.
That's about it, in a nutshell.