Hi Jennifer,
I've been on a Medtronic insulin pump for ten years. It's wonderful. It helped with the stress of dealing with diabetes through teenage years. It's a wonderful piece of technology.
As for wearing it at night and on the beach etc... I no longer use a clip for mine but you can clip it to a pair of boxer shorts, underwear, or whatever you wear to bed. I hardly notice it anymore. I've never had it fall off of my bed or any problems sleeping with it. The worst that's happened is waking up with the tubing wrapped around me like a belt. The beach is a little tricky but if you're in a swim suit and don't plan on going in the water it's really easy to clip it just about where ever you want if you're using a clip, or just tuck it inside if you're not. When you do take it off put it in a baggy if you're worried about the sand. Then tuck it inside a bag or a towel to keep it out of direct sunlight. I'm not sure what kind of set you plan on using. I use a silhouette and keep it in my stomach. I've never had sand get inside of it, and although on occasion it's come out due to water, it's never been a problem for me. They're very easy just to put in again in a bathroom as long as you came prepared. It's really really easy to disconnect the pump if you need to and as long as you are prepared for what you plan on doing during the day your blood sugars won't suffer.
Try not to worry, the pump is amazing. It's been such a blessing in my life. After a while it becomes a part of you and it's not a hassle to carry around. Try out the different pouches minimed makes and see if they work for you. If not try something else.
Hope this helps.