Hi YaYa,
Have fun in Las Vegas... I have been there many times and it's a lot of fun. As for flying, I've traveled extensively all over the world these last 20 years, and sometimes getting through the scans is easier than others. I always carry all my ostomy supplies on board with me in a carry-on, but I also keep a quick change package in my purse or tote in case of an emergency. I'm also a diabetic and am on a lot of medications/insulin. I have syringes as well as a BiPAP for sleep apnea. So if anyone is going to get checked, it is me. But I rarely have a problem. I fly to Australia every year to visit my son and his family who live there, but this last year was the first time I had difficulty being scanned. I'm also a bit "perverse". So when they couldn't see my ostomy/pouch clearly, they asked me if I could pull up my pants more (I wear pull-ons, not a belt). I looked her in the eye and said, no I couldn't. I didn't know what the issue was, but I had never had the problem before. They rescanned me and let me through anyway.
I take it all in stride, considering the number of syringes I need to take with me for a 4-week stay in Australia (8 shots a day). I'm a walking pharmacy, but as I said, I never really have a problem. As for eating and food, I don't worry about that either. I always use the restroom before I board, so I don't have to fight my way to the restroom immediately. Because I'm a diabetic, I also bring my own food snacks on board since the trip to Australia is 19 hours, and I never know what time they're going to feed us. But with the short trip you'll be taking, you don't have to really worry about it. I don't bother buying another bottle of water, but I bring an empty water bottle through the screening process and use a water fountain to fill it up. When I board the plane, I always ask for a bottle of water. They always have one available...
So, relax and enjoy your trip... and just go with the flow.
Marsha