S.G.
It's so hard when they are this age to have to deal with the separation yourself and to have to help a child to cope as well. I'm over here in Beaufort and my hubby is a Marine. I'm with the FRA with his squadron and the FTB (Family Team Building) that is for the whole base.
You are probably going to have to repeat yourself over and over for a little while to her till you get the house on a routine. Then it will get easier for all 3 of you while he is gone. In the mean time, let her draw pictures to send to him, write letters to him for her. Take pictures of the kids playing, doing daily activities of of new milestones like tying shoes or riding a bike. The more he knows you've got things under control at home, the easier it makes the deployment for him especially if he is in a war zone. He can focus on the mission and get back home to you and the kids. Make a paper chain with the kids out of construction paper. Each loop is a day he is gone and you write on it something that happened that day be it good or bad. As your chain gets longer, you can hang it in the house and you have an instant welcome home decor and something for him to read when he gets readjusted to being back home. Another great idea for the kids (your 3yr old would probably love this!) is a Daddy doll. https://www.hugahero.com/ You send in a pic of your hubby and these guys turn it into a doll that the kids can sleep with, snuggle, talk to, etc. Also, there is Military One Source. http://www.militaryonesource.com/ This is a free service to you and has a more information than you could ever imagine!! You can get info online or you can all their 800#. Everything they offer is FREE too!! They can help you from finding a phone number to free tax prep service though H & R Block at tax time (I use this every year!) You can get counseling for yourself of the kids, tips on deployments, homework, anything!
I also know there is a company that makes free banners for wives of deployed too, all you pay is shipping. If you'd like, I can find out that info for you. Just let me know.
If your FRG offers any activities for you or the kids, do it. If they don't then they are doing all of you there a disservice. Our Squadron does something every month for our families deployed or not. If you need more ideas or resources, ask me! I'm sure there is more but it's early and I haven't made it through my first cup of coffee yet! lol
{{HUGS}} Hang in there, it will get easier I promise!!
S.