When shopping used be careful. There are some sweet deals out there but, there's more money pits. I would try to stay in the 1990s and get at least throttle body injection. Carbs are fine but TBI warms up better and gets good gas mileage (well, motorhomes suck the gas but..). Most any brand will do, Bounder, Winnebago, etc.., all good. Personally, I'd pay more attention to the chassis and the condition of the house. If it has significant water damage run away as fast as you can. Small leaks that were immediately addressed aren't a deal breaker for me. It's a judgement call. Ford and GM have both made decent chassis. I'm not alergic to either.
In old motorhomes there's no meaningful difference in price between A and C. So get as much as you can for your money. But, avoid a big C class with a small V8. Get a big engine.
As far as having 120 VAC off the chassis, you can run an inverter. But, you're limited on how many watts unless you add some batteries, etc.. It's simple to do that and not terribly expensive (Depends on how many batteries you have on board already. I have one house battery. I'd want more if I was looking to use it more often.)
Get a motorhome with a generator. We use the heck out of ours. Not optional for us.
For wireless internet, there are a few out there that are prepay like Virgin, etc.. That might suit your needs. Check Walmart.
When you're looking for an old motorhome consider what you can fix, what you can,t and/or what you can live with.
