Absolutely yes. Anybody and everybody should know it.
CPR. It may be a good idea if she is alone with the kids.
Sure. But don't expect him/her to learn if u havent.
AHA sponsored course. The american heart association sponsors official CPR course (infant and adult) for which you can sign up for on line.
Fire station. Check w/ your local fire department, often they offer certification courses.
Red cross. I would suggest contacted the red cross to look into whatever courses they provide. Also, some hospitals and community groups also provide CPR instruction courses.