You can keep the fridge running while underway. There are certain bridges and/or tunnels when you might have to shut the propane off but for the short duration your food will be fine. A number of years ago one of the members actually did an experiment as to how long the fridge will stay cold and it's much longer than you will drive in a day providing you don't keep opening the doors. When we had our 5th wheel we often still kept a small cooler in the truck and would just stock that as necessary. As far as other advice...
1. Relax.
2. Go slow at the beginning.
3. Don't expect everything to be perfect. It's not going to be. Expect equipment failures, traffic, lousy campgrounds, getting lost, bad weather and the unexpected.
4. Just roll with #3.
5. Remember that despite some of the "rolled eye" responses you may get (and yes, I'm guilty of that too) ALL of us were newbies at one time or another. EVERYBODY has made mistakes.
6. Mistakes, like arguments, are not a problem. It's how you handle said mistakes (like arguments) that counts. Some just teach "heartier" lessons than others!
7. We're a family. The vast majority of us will drop everything to help another RVer. Thanks to a more experienced RVer and a truck driver, our first trip in our Endura was not a disaster.
8. Enjoy this country and all it has to offer. There is as much adventure 30 miles from your house as there is 300 or 3000 miles away. Or as much "ahhh". Hubby calls it "oohsah". It's the place you go in your mind when you need to chill.
9. You will NOT save money by RVing. It's a lifestyle, not a cost-saver.
10. You do NOT have to justify RVing in anyway by commenting on bedbugs, sleeping in someone else's bed, etc. You RV because you WANT to.
11. Some people just don't get the "lifestyle". That's OK. That means one more empty site at a campground.
12. Enjoy!