Jason called a RV rental company (getrv.com) and here is the info they gave him:
1. Where to park & sleep: there is ample information on their website and it seems we will not have any problem.
2. Driving the RV: we can drive most vehicles using Australian/Spanish licenses, however, drivers must be >= 25 years. I guess it depends on the rental company…anyway, Pablo and Jason are over 25 years old.
3. Driving inside big cities: We can drive ‘anywhere’ in the US, including big cities.
4. How to refill water deposit / what to do with the sewage / electricity when not driving: Sewage and water lasts around 1 week. Can be refilled or disposed of at most gas stations. For electricity, most models come with a generator.
Thanks to Jason for calling them and I think what we should do next is just…renting the RV!