It will depend on what resolution you want but I would probably go for 1/8 and set the steps per accordingly.
Attenuation I imagine is to tune out the mid band resonance that steppers can be bothered with. If it is then suppose it will be trial and error.
I prefer quality switches such as Honeywell 14CE/914CE Series, they are expensive but I have large machines so prefer to err on the side of safety. Having said that my Bridgeport has optical switches and they work well, I use Optek OPB917B and have them in a housing with a spring loaded plunger sticking out either side, the plunger is held central by the springs to block the switch when inactive.
If its a small machine you have then I would look at opticals or even just some of the micro switches, they are cheap enough.
Hood