Is there a reason to upgrade Internet Explorer on Windows Server?
Keep in mind that while you may not directly use IE, the IE rendering engine or other components may be used by other applications you may run.
I think it should kept it up to date.
Definitely. If you have it installed, I'd rather run a more the most up-to-date version regarding security. Featurewise it's a moot point, but I'd rather not have admins browsing around in IE6 on my servers.
Optimally noone uses IE on servers, but we know sh** happens.