[Arubalisa]

Yes, Aruba drives on the right hand side of the road as here in the US. International driver's license is NOT needed.
http://www.aruba.com/whattodo/traffictips.php

Stores in Oranjestad are closed on Sundays with the exception of when there is a cruise ship in town. In that case, some of the stores will open afternoon from approx. Noon to 5 p.m.

Use this schedule http://www.arubabycruise.com/stats/index.html to determine, if and when cruise ships will be in port while you are on the island. An important consideration when booking excursions as well. Those are usually the best days to just hang out at the beach.