I'd suggest to look at floor plans, maybe take in an RV show, if you are totally new, and describe on paper the differences found from research between the different brands. The description page may widen your views or narrow your choices. Having it written allows you to reference it when shopping or looking at RV's.
Yes, some of the bigger and better trailers have a built-in generator option. Some owners choose to operate smaller generators they bring along. It can be about noise and fuel savings when generating power. An alternative accessory is solar charging, an option better discussed in the Tech Issues" section of this Forum.