Welcome to the forum, and congratulations on your purchase! This is a great place to bring your questions, a wealth of knowledge here willing to help you.
As to the driving school, that should be mandatory! Check with Lazy Daze near Tampa. They do a class, then everyone has a chance to drive a new Class A around a course. My co-pilot and I both did the course, even though i do all the driving. She's my emergency back-up driver, and needs the confidence to take over if necessary. There are some online videos, too, but you miss out on the Florida sun!
You are unlikely to have a height clearance problem on main roads, you'll clear anything a semi will. Know your height, and put it on a label right in front of you on the dashboard with it. Bridge height is always warned with a sign, just watch for them on backroads. Most GPS won't help you with that. Oh, and if you forget to put the TV antenna down, you might leave it on the highway! (Note my tagline!)
Forget the tachometer, your automatic transmission will take care of all that. Drive a comfortable speed, and don't worry about keeping up with the speed of traffic. So what if you slow them down for a minute or two? Higher speeds=lower mpg.
Some folks are "wanderers" who travel without a plan, and some are "planners" who carefully plan out an agenda. We take our time in the mornings, travel 300 miles most days, and like the smaller towns. We use a free app called RVParky to locate campgrounds and places that allow boondocking in their parking lot with no connections. We especially like the Crackr Barrels that allow RV's overnight.
If all else fails, read the directions!!