New to RV's, couple quick questions

In buying a used RV class A start at the top, as if it needs a new roof the run about $4,500 for a 36 foot RV. If the roof has leaked or will leak, the interior will be rusted and full of mold. Then if you are happy with the interior condition and layout then make sure everything works like oven, stovetop, heater, water heater, fans, alarms, TV's stereos etc. Then you are left with the tires, brakes, engine AC, radiator, etc. Best to have a mechanic check the elements you are not able to do yourself. You need to understand that the vehicle has to be roadworthy for safety and convenience. You can spend now on an inspection by an expert or pay later for repairs that could be more than the unit is worth. As far as running the generator, it is usually best to use it as needed not continuously, as the interior lights and pumps for water are 12 volt and run off your house batteries, that are usually 2 deep cell 6 volts tied together for 12 volts. Those batteries recharge when generator is on and when you are driving, but need to be checked for fluid level as charging evaporates interior acid fluids. Then you have propane that heats hot water, interior heater, and stove burners. Propane also runs the refrigerator when electric is off, as it is 120 Volt and only uses 12 volt to start the propane, when 120Volt is off. That refrigerator has to be close to level to allow the system to work, that's where leveler legs if present on RV are used. If it does not have a working leveling system blocks have to be used and are a real pain to level and can be dangerous due to slippery soils. So don't look, inspect and use someone that knows RV's to determine the value. Most sellers will listen to an experts valuation and adjust their asking price to the market value indicated by the analysis.