Country/region table - best practice

Looking for both examples and advice on how the Country/region table should be used.

We understand the ISO code. It is more the Country/region and Description that get a little fuzzy.

How do you use the Country/region (COUNTRYREGIONID)? Do you use the ISO code, do you use a shorter version of Description (China rather than P.R. China, etc) or a different option?

If you use tags with the country of origin on them, do you use the Country/region or Description?

Some examples, what do you have for country/regionid for Canada, Switzerland, India?

How would you set up Tahiti?

Thank you