I am new to trailer travel, but am about to jump in up to my neck with my father's fifth-wheel. My parents travelled the country, starting with campers on the back of a variety of pickups with succes...
There are many posts on sanitizing the fresh water. I never have for the simple reason that we get enough treated city water so that there has never been a problem in 30 years.
And there are even more posts on tires. There are numerous sub standard tires available. Be aware that very few tire shops know anything about RV tires but they will have a good sales pitch anyway, if it fits they will mount it. RV tires are not subject to the same conditions as a standard car tire.