Not my kids but a friends DS has chicken pox and she took her out shopping the day after coming out in the spots, so very contagious.
I thought you weren't suppose to take them out (unless it cannot be avoided), particularly the risk to pregnant women etc. A friend said it didn't matter because you are contagious before anyway but I think its different then as you don't know. Surely taking a child out with some highly contagious is irresponsible?
Haven't had to deal with CP yet so no idea.