Welcome to the Forum!
I can't answer all the questions, but I'll address some of them.
1) Most Motorhomes come with A/C units (some ducted, some not) and propane fired furnaces. Propane is not the most efficient method of heating a RV, more heat is vented out of the RV than goes into the RV. RV furnaces burn through propane quickly. If you have an electric hookup or have a generator, space heaters are a popular method to supplement the propane furnace.
2) If we need to stop before our destination, we usually just park in a Walmart parking lot, if they allow it, sleep 6 - 8 hours and get back on the road. If we plan to stop longer than that, we'll check into a campground. Depending on the state, Highway rest stops are an option as are Truck Stops and other big box stores.
3) Most RVs (except maybe pop-ups without showers) have waste holding tanks. When they get full you dump them. If you are in a campground with full hookups the sewer will be right at your site. If sewer hookups are not available at the site, usually there is a dump station (often times near the exit) that you can dump your tanks. Flying J's have dump stations, but they usually charge for it. There are also highway rest stops that have dump stations. Or you can call a Honey Wagon to pump it out.
4a) Quality is suggestive, what some think is high quality could be junk to someone else.
5) Some campgrounds offer Free or pay for WiFi. Some throughout the campground, some only in certain parts of the campground. You can also use a Smartphone that allows tethering (can be used like a modem) or works as a WiFi hot spot. Or you can buy a dedicated Broadband WiFi router like Verizon's MiFi. You pay for the device, like $50 - $100. Then pay for the bandwidth on a monthly basis. There are also prepay devices that do the same.
6) Definitely gas (or diesel). Like a car or utility trailer, RVs have to be registered with your state's DMV. If it is a Motorhome, then you have to have Auto Insurance. Like any vehicle with an engine, a Motorhome will require periodic maintenance and repairs.
7) My main concern with our RVs is water leaks. Nothing kills a RV quicker than water in places it shouldn't be.
-Michael