The only way to have both a text and drop-down field would be to create both of those fields, which could get confusing.
If you're interested in *testing* a change that may work for countries, there's a minor code change you can make below. If you edit the /plugins/jfbcprofiles/jomsocial.php file, around line 522, you'll see the following line:
$query = 'SELECT * FROM #__community_fields WHERE type="text" OR type="textarea" OR type="date" OR type="birthdate" ORDER BY ordering';
Update that to the following (adding the --OR type="country"--)
$query = 'SELECT * FROM #__community_fields WHERE type="text" OR type="textarea" OR type="date" OR type="birthdate" OR type="country" ORDER BY ordering';
That will add the Country field to the Field Map area of JFBConnect Profiles. Then, set the correct Country field from Facebook to import into it. It's likely that the countries from Facebook will 'align' with what JomSocial allows, but there may be some countries that don't work perfectly. However, if you expect the majority of your users to come from the 'major' countries, it will hopefully work as expected. Please, please, please test and let us know how well the field gets imported and if it seems correct with the options available in JomSocial!
Some things to look for are is that Facebook (I believe) will return "United States". I don't know what JomSocial uses, but if it's U.S.A or United States of America, that would look like 2 different countries that your users may be from.
Good luck, and keep us posted,
Alex