Please excuse my ignorance in this, but when I do a lookup, and the SOA has
, say, 4 nameservers, which one would likely to repsond to me a
geographically close NS? Or the primary first, or does it work on a "I don't
care where you are" round robin principle?

I am curious because I have 3 secondary servers about to be used, 2 in the
U.S and 1 in the UK, along with the primary NS located here in my country,
on a small (64k) ISDN line, which can be very congested at numerous times
24/7 due to the nature of the business. So, would it be more beneficial to
have one of the international NS's act as primary? If it matters, there is
about as much local as international traffic connections here, so choosing
one ofver another for "best usage" would not really matter.