The vast majority of the time your home (US) drivers license is sufficient, but some places (Bali comes to mind) the cops will stop tourists & demand an International Drivers License & then shake you down for a couple of bucks if you don't have one. They're usually free from your Automobile Association (AAA in the US) but not generally needed. They basically say the same things as your normal drivers license, but in lots of different languages.
Yes, we have a house near Seattle
which is usually rented out (& provides much of our cruising income). The problem with this, of course, is that we can't stay in it when we come back to the US, forcing us to "couch surf" with friends. Or, as one friend put it "Skipping from Bed
with all the frequency of a cheap
Yes, our kids
miss the cruising life almost as much as we miss them.