i am a nurse and this is the info i can give you.
yes you can catch chicken pox more than once
you can only catch chicken pox if you come into physical contact with it.once the spots have scabed you are not contagious
you can catch it before they appear on the carrier as they are already carrying it (via saliva and skin to skin contact.
chicken pox is usually not harmul to unborn baby unless early in pregnancy,if you have chicken pox the baby will have chicken pox also.
it is not related to rubella
nikki