Especially when you are gone, what is everything you can to do make sure your family is protected when you are away?
I know you can have a housecarl there to protect them, but can you get more than one person to stay at the house? What all can you do to ensure safety?
Apart from scripted kidnappings, your family is always safe while you are away, it is only when you are there that they are in danger. Your children are safe from everything except game glitches that make them vanish, but if you give them some good daggers they will sometimes help out with the fighting. It is your spouse you need to protect, and hopefully you would also help protect anyone else at your house. Give them some decent weapons, health potions and make sure you quickly kill anything that turns up to cause trouble. Unfortunately your chickens, cow and the house horse tend to die pretty easy, so they are not so easy to protect.