A) You can pick up a key @ [link] or here: [link] (Both of these sites have goodies for other projects too...) B) You can go crazy with a ton of diff. standard mice. Mine was done using this particular model: [link] This one worked for me especially well, because the guts snap right into the brass base of the morse key like it was built just for it. (I killed half a dozen mice looking for one that "fit", btw... )
Let me know if you need anything else. I'm sure whatever you do will be more flash than my spartan design.