About the only regret you will have is that 4 days isn't nearly enough time in Yellowstone. You will be able to see most of the highlights, but to truly see and enjoy the park one needs 1-2 weeks. Enjoy your stay and begin thinking about your next trip to Yellowstone.
Fishing Bridge RV is not a place to just hang out at your camp site. It is a little tight but most don't have any problems. Most of your time will be spent away from the campground. Plan on taking your lunch with you or plan on buying something at one of the visitor centers.
Enjoy your time there,
Keith