First of all, do not "train" your wife. It will not go well. Have your buddy or actually I would recommend a certified NRA instructor, instead of a cop, go through the basics with her alone, without you around.
As far as firearms go, that should be her choice also, so as part of her training maybe rent her a few different pistols, or better yet, ask her which she'd like to try. My wife prefers my HK P7M8, and P7 PSP to all my other semi's except for the Ruger MK II's which is what she shoots most of the time. However, not for self defense purposes.