I don't always layer my drums, but when I do I put them on different pads in Ableton Drum Rack, leaving them on different midi notes. I prefer copying the midi notes instead of triggering all layered sounds with one midi note. I'm more flexible that way and can set accents by taking out one of the layered sounds here and there.
Processing wise I do what ever is needed. I tend to EQ and filter the sounds individually and process the dynamics in a group.
Btw, you say you have a pretty decent style of layering samples. Don't you want to share it?