You may use the conventional short names or abbreviations. However, each hint is based on the country's full, English name, so be careful with countries like Micronesia or the Congos.
I based the time on the fact that Countries Of The World is 15 minutes, and there are only 20 countries here, then adding extra because it is a mind-twist (and yellow box). I am open to adding more, however, if there is a groundswell of support.
I think he's questioning whether "Y" is a vowel in Seychelles. I am honestly not sure it's the best country to include since it's quite hard to say whether it's a vowel or not. Is "Sey" pronounced as a diphthong? Otherwise it might technically be a consonant.