To answer your last question.
Dual curling irons/curling brush are available. I carry one all the time. It is automatic, so adjusts to whatever current you use, with an adapter. However, I tried to heat it up in the "shaver only" plug and it did not heat; I made sure it was unplugged from there so it wouldn't start a fire--in case.
Shavers. My husband buys the portable ones that use batteries for traveling. There may be dual voltage shavers. His regular shaver is much heavier and doesn't give as good a shave as the portable ones.
We've lived overseas 23 years, and are traveling over 14 years since we retired, and 'Ive used the dual curling irons all these years, so when I'd get back to the States, I'd have one that works there too. He found it was easier and lighter to carry the battery operated shavers.
Our dual voltage hair dryer was purchased at a travel store, but it didn't have a lot of settings. If we carry a travel iron, we buy dual voltage; normally we don't carry one now.
We make sure we have enough adapters, for different parts of Europe, Australia, Great Britain, etc. You can buy on line, but we usually go to a travel section of stores, or luggage shop. One out now for Europe has several ways to plug in appliances/tech items, depending if you need a polarized plug, no polar plug, round high, round low. So one fits all. But, I think they are a bit flimsy for the price.
Almost all tech items are automatic dual voltage, like e-readers, net books, laptops, tablets, dvd players, even portable oxygen concentrators, cameras, etc. I used to have a portable Canon printer for use in Japan when I traveled for business, and it was dual voltage, and as small as a roll of tin foil.