NZ and USA are the only countries in the world to allow it.
No, a ton of others also allow it but there might be more more (or fewer) restrictions. But yes, advertising pharma products is pretty weird. Your doctor should proscribe your meds and you should not ask for something specific because an ad told you so. And many of those proscription free cold medicines are not really necessary or effective anyway.
Yes but also expect to pay more. IIRC they will honor google's pricing for the first year but afterward you more likely than not have to pay more. And you might lose some features you use.