I would recommend the 25' hose for water hookup. Most dump stations have a water hose for flushing your dump hose and cleanup around the area. Try taking short trips close to home to learn about RV camping and observe other campers. Try asking questions of other campers as most campers are willing to answer questions as they went thru the same learning curve.
It is best to list your year and model of Rialta at close, as there are differences in models.