I have a few questions about flying. Please help. I have never been on a plane trip.?

Okay so my friend and I are going on a plane trip. Neither of us have flown before. We are flying from Washington D.C to Los angeles (non-stop direct flight) to visit a friend who goes to school out there. First question. I'm about to book my flight and hotel through orbitz. 5 months in advance.(we plan on leaving in October) Were both in the U.S Army, national guard. If I buy the tix and room, and let's say a month before were suppose to leave our army unit get's deployed, can I get a refund? Since now we can't go? Like can I get my 1500$ back? Or no? Second thing. Like I said we have never flown before, were pretty nervous, what are some good tips to help us relax? lol. Can we drink alcohol on the plane? Do they serve? What about food? Is there anything to eat on the plane? If so how much does it cost? We are flying coach if that means anything.