Thanks to everybody for responding with helpful information; much appreciated! Any concerns re picking up a bug when eating street food radnub? We'd love the authentic experience, but are just a bit cautious. Do you take anything along just in case?
One thing I forgot to ask is about mobile WiFi. We rented a devise last year in Japan which was invaluable. I'm reading that buying a SIM card in Vietnam is a good way to go. We used it a lot for train schedules, maps and to book accommodation without having to look for a hotspot. What do others do. Thanks again.