depends, for example, Australia where i'm from only offers the 1049 convention for IDP, which means that you cannot use it in countries that are only signatory to the 1968 IDP, for example, Vietnam.
Yes, but they give you a 2 year "temporary" license. then a 5 year. It seems some people are going to renew their 5 year, on the DTV and only getting a 2 year. Doesn't seem like a big issue, until you try to get your Thai IDP (live in thailand and want to drive in Japan for example) and they wont issue it because you don't have the right license.