I recommend you and your children see a crisis counselor. First and foremost, if you haven't already been in contact with the Red Cross, I'd start there. The Red Cross, often helps families who've endured catestrophic loss such as natural disasters, and even fires. The Red Cross is often only associated with world events like Katrina or the S.E. Asian Tsunami, but they have local chapters that provide shelter, food, and crisis counselors, which it sounds like what you and your children desperately need right now.
If the Red Cross doesn't work out for you, try Catholic Charities, Lurtheran Social Services or your church or synogogue if you belong to one. They often have connections and good social services resources, including mental health services.
In the interim of finding crisis counseling do not deny your childs needs during this critical time. I'm sure you know she's not really misbehaving, just try to keep in mind she's too young to communicate her feelings and fears and it's coming out in inappropriate ways. Remind your son of this also, so he doesn't take her attacks personally. Your daughter is clearly full of fear and uncertainty about her safety and well-being and is in defense mode.
If she needs holding, hold her tight and add kisses too. If she needs to be in a crib and it makes her feel safe, just forget the crib and cuddle her in your own bed instead. You're so right, this IS a really traumatic thing for a child to go through. I suspect your older child is suffering too, but is probably a little better equipped to manage his feelings because he's older. But he's probably needing extra attention too but just isn't talking about it.
The effects of something like this could be lasting for all of you. You are all still in shock, and after the shock wears off, will really need some type of intervention beyond the physical stuff like housing.
I know finding the extra energy and patience to help your children right now has to be incredibly difficult and overwhelming. Especially when you need a hug, comforting and words of assurance too.
I suspect you are in crisis too (not just physical but psychologically speaking)and will be for sometime. And finding the ability to comfort your family while trying to find a place to live and figure out the next step must feel monumental. Just do the best you can muster. Look for added support for yourself in the process.
If possible, perhaps see if you have a close relative the children can stay with for some sense of stability until you find a new home and give you more freedom to focus on the day to day details of getting your life back in order.
Perhaps send the to a grandparent's house or an aunt/uncle with children would be great, as this might take their mind off their troubles for a while, and they'd be in familiar surroundings. Especially if you think you'll be in this situation when school starts. Maybe they can stay with the relative during the school year if you think it will take that long to recover.
While figuring out the next step is important, and despite the less than perfect living situation, I think right now it's really important that you all step back each day and make quiet time so that you and your family can regroup, vent, comfort, coddle and cuddle. Your families mental well-being depends on it.
I'll you keep you in prayer. Keep us posted.