I'm about 4 days away from being done with our second deployment; he's on his way home after 15 months. Its scary and its big, I know. The important thing to remember is that you can do this. You can get through and survive and even thrive.
Depending on where he'll be, he should have access to email and phones on a pretty regular basis. My husband and I had times that he would call. Mainly on Saturday or Sunday around noon. If I was working, I let him know to call the next day or a different day. It helps to cut down on the stress of being attached to your phone.
If you have time, have him record a few videos for your girls. Talking to them, reading a bedtime story, singing a song. Those videos will help your girls tremendously throughout your time apart. There is also the Elmo deployment DVD; most FRGs have it or know where to find it.
As for you, this is your time to explore and grow. Take an art class, or photography or a cooking class or take up a new hobby (knitting, screenprinting, etc) I have a girlfriend that resolves to teach herself something new each deployment. First time around, she took lots of craft classes. Second time, she became an excellent cook. This time, she's taking private flying lessons and glass-blowing lessons.
Packages are a great way to let him know you're thinking about him. There are so many ideas out there. I'm going to point you towards the Operation Homefront Dealing with Deployment forums:
Dealing with Deployments - Forum Powered by eve community
One of the first few threads in that forum is a Care Package Idea and Tips thread. It has pages and pages of great care package ideas. The rest of the forums can get sort of crazy, but DwD is always a good escape; you can post and find almost instant support.
As far as working, thats an excellent idea. It'll keep you busy and allow you to save more money. Deployment money is tempting; it gets spent very easily. The best thing to do is set up an allotment to save a huge chunk of it. At the end of the deployment, you'll have a massive savings account. For a downpayment on a house, or the start of a retirement account, or whatever else you'd like.
I'm imagining you're at Ft. Drum in NY. You're close to the base, so thats good for support. Do you have the girls enrolled in CDC? That's a good thing to do so that if you have an emergency and need to be somewhere quickly, you can drop the girls off and not worry.
Also, its icky to talk about, but does he have his Will and Power of Attorney for you? Normally JAG will come in and help you with that stuff before deployments, but sometimes command's don't get them to. They are important documents. You need to get them ASAP. And if you feel inclined, a passport. If he's injured (which he probably won't be), they send them to Germany. If you already have a passport, you can be on your way within 24 hours. If you don't, it can take up to 2 weeks before you can get there. Its an unlikely scenario, but you want to plan for the worst.
Gosh, I've written a book. If you have anymore questions, please feel free to PM me.
*Hugs* You can do this. It's going to be okay. I promise.